diff --git a/vm/archlinux-vm.sh b/vm/archlinux-vm.sh
index 6fa640de7..e5c438ecd 100644
--- a/vm/archlinux-vm.sh
+++ b/vm/archlinux-vm.sh
@@ -403,18 +403,24 @@ function advanced_settings() {
     fi
   done
 
-  if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
-    if [ -z "$MTU1" ]; then
-      MTU1="Default"
-      MTU=""
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+  while true; do
+    if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
+      if [ -z "$MTU1" ]; then
+        MTU1="Default"
+        MTU=""
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      if [[ "$MTU1" =~ ^[0-9]+$ ]] && [ "$MTU1" -ge 576 ] && [ "$MTU1" -le 65520 ]; then
+        MTU=",mtu=$MTU1"
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      whiptail --backtitle "Proxmox VE Helper Scripts" --title "INVALID INPUT" --msgbox "MTU Size must be a number between 576 and 65520, or leave blank for default." 8 58
     else
-      MTU=",mtu=$MTU1"
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+      exit-script
     fi
-  else
-    exit-script
-  fi
+  done
 
   if (whiptail --backtitle "Proxmox VE Helper Scripts" --title "START VIRTUAL MACHINE" --yesno "Start VM when completed?" 10 58); then
     echo -e "${GATEWAY}${BOLD}${DGN}Start VM when completed: ${BGN}yes${CL}"
diff --git a/vm/debian-13-vm.sh b/vm/debian-13-vm.sh
index 26c7fd0f4..7cedd9e74 100644
--- a/vm/debian-13-vm.sh
+++ b/vm/debian-13-vm.sh
@@ -418,18 +418,24 @@ function advanced_settings() {
     fi
   done
 
-  if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
-    if [ -z "$MTU1" ]; then
-      MTU1="Default"
-      MTU=""
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+  while true; do
+    if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
+      if [ -z "$MTU1" ]; then
+        MTU1="Default"
+        MTU=""
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      if [[ "$MTU1" =~ ^[0-9]+$ ]] && [ "$MTU1" -ge 576 ] && [ "$MTU1" -le 65520 ]; then
+        MTU=",mtu=$MTU1"
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      whiptail --backtitle "Proxmox VE Helper Scripts" --title "INVALID INPUT" --msgbox "MTU Size must be a number between 576 and 65520, or leave blank for default." 8 58
     else
-      MTU=",mtu=$MTU1"
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+      exit-script
     fi
-  else
-    exit-script
-  fi
+  done
 
   select_cloud_init
 
diff --git a/vm/debian-vm.sh b/vm/debian-vm.sh
index 5c67b0999..3f6a1ba13 100644
--- a/vm/debian-vm.sh
+++ b/vm/debian-vm.sh
@@ -408,18 +408,24 @@ function advanced_settings() {
     fi
   done
 
-  if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
-    if [ -z $MTU1 ]; then
-      MTU1="Default"
-      MTU=""
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+  while true; do
+    if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
+      if [ -z "$MTU1" ]; then
+        MTU1="Default"
+        MTU=""
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      if [[ "$MTU1" =~ ^[0-9]+$ ]] && [ "$MTU1" -ge 576 ] && [ "$MTU1" -le 65520 ]; then
+        MTU=",mtu=$MTU1"
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      whiptail --backtitle "Proxmox VE Helper Scripts" --title "INVALID INPUT" --msgbox "MTU Size must be a number between 576 and 65520, or leave blank for default." 8 58
     else
-      MTU=",mtu=$MTU1"
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+      exit-script
     fi
-  else
-    exit-script
-  fi
+  done
 
   if (whiptail --backtitle "Proxmox VE Helper Scripts" --title "CLOUD-INIT" --yesno "Configure the VM with Cloud-init?" --defaultno 10 58); then
     echo -e "${CLOUD}${BOLD}${DGN}Configure Cloud-init: ${BGN}yes${CL}"
diff --git a/vm/docker-vm.sh b/vm/docker-vm.sh
index 4a388e6b1..a7fa7dba5 100644
--- a/vm/docker-vm.sh
+++ b/vm/docker-vm.sh
@@ -348,17 +348,24 @@ function advanced_settings() {
   done
 
   # MTU
-  if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
-    if [ -z $MTU1 ]; then
-      MTU1="Default"
-      MTU=""
+  while true; do
+    if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
+      if [ -z "$MTU1" ]; then
+        MTU1="Default"
+        MTU=""
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      if [[ "$MTU1" =~ ^[0-9]+$ ]] && [ "$MTU1" -ge 576 ] && [ "$MTU1" -le 65520 ]; then
+        MTU=",mtu=$MTU1"
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      whiptail --backtitle "Proxmox VE Helper Scripts" --title "INVALID INPUT" --msgbox "MTU Size must be a number between 576 and 65520, or leave blank for default." 8 58
     else
-      MTU=",mtu=$MTU1"
+      exit_script
     fi
-    echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
-  else
-    exit_script
-  fi
+  done
 
   # Start VM
   if (whiptail --backtitle "Proxmox VE Helper Scripts" --title "START VIRTUAL MACHINE" --yesno "Start VM when completed?" 10 58); then
diff --git a/vm/haos-vm.sh b/vm/haos-vm.sh
index 802d6b883..1cdac8b27 100644
--- a/vm/haos-vm.sh
+++ b/vm/haos-vm.sh
@@ -487,18 +487,24 @@ function advanced_settings() {
     fi
   done
 
-  if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
-    if [ -z $MTU1 ]; then
-      MTU1="Default"
-      MTU=""
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+  while true; do
+    if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
+      if [ -z "$MTU1" ]; then
+        MTU1="Default"
+        MTU=""
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      if [[ "$MTU1" =~ ^[0-9]+$ ]] && [ "$MTU1" -ge 576 ] && [ "$MTU1" -le 65520 ]; then
+        MTU=",mtu=$MTU1"
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      whiptail --backtitle "Proxmox VE Helper Scripts" --title "INVALID INPUT" --msgbox "MTU Size must be a number between 576 and 65520, or leave blank for default." 8 58
     else
-      MTU=",mtu=$MTU1"
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+      exit-script
     fi
-  else
-    exit-script
-  fi
+  done
 
   if (whiptail --backtitle "Proxmox VE Helper Scripts" --title "START VIRTUAL MACHINE" --yesno "Start VM when completed?" 10 58); then
     echo -e "${DGN}Start VM when completed: ${BGN}yes${CL}"
diff --git a/vm/mikrotik-routeros.sh b/vm/mikrotik-routeros.sh
index 1ba2b7805..4121a327e 100644
--- a/vm/mikrotik-routeros.sh
+++ b/vm/mikrotik-routeros.sh
@@ -470,18 +470,24 @@ function advanced_settings() {
     fi
   done
 
-  if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
-    if [ -z $MTU1 ]; then
-      MTU1="Default"
-      MTU=""
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+  while true; do
+    if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
+      if [ -z "$MTU1" ]; then
+        MTU1="Default"
+        MTU=""
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      if [[ "$MTU1" =~ ^[0-9]+$ ]] && [ "$MTU1" -ge 576 ] && [ "$MTU1" -le 65520 ]; then
+        MTU=",mtu=$MTU1"
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      whiptail --backtitle "Proxmox VE Helper Scripts" --title "INVALID INPUT" --msgbox "MTU Size must be a number between 576 and 65520, or leave blank for default." 8 58
     else
-      MTU=",mtu=$MTU1"
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+      exit-script
     fi
-  else
-    exit-script
-  fi
+  done
 
   if (whiptail --backtitle "Proxmox VE Helper Scripts" --title "START VIRTUAL MACHINE" --yesno "Start VM when completed?" 10 58); then
     echo -e "${GATEWAY}${BOLD}${DGN}Start VM when completed: ${BGN}yes${CL}"
diff --git a/vm/nextcloud-vm.sh b/vm/nextcloud-vm.sh
index 50d0a7171..cee5829bc 100644
--- a/vm/nextcloud-vm.sh
+++ b/vm/nextcloud-vm.sh
@@ -406,18 +406,24 @@ function advanced_settings() {
     fi
   done
 
-  if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
-    if [ -z $MTU1 ]; then
-      MTU1="Default"
-      MTU=""
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+  while true; do
+    if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
+      if [ -z "$MTU1" ]; then
+        MTU1="Default"
+        MTU=""
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      if [[ "$MTU1" =~ ^[0-9]+$ ]] && [ "$MTU1" -ge 576 ] && [ "$MTU1" -le 65520 ]; then
+        MTU=",mtu=$MTU1"
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      whiptail --backtitle "Proxmox VE Helper Scripts" --title "INVALID INPUT" --msgbox "MTU Size must be a number between 576 and 65520, or leave blank for default." 8 58
     else
-      MTU=",mtu=$MTU1"
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+      exit-script
     fi
-  else
-    exit-script
-  fi
+  done
 
   if (whiptail --backtitle "Proxmox VE Helper Scripts" --title "START VIRTUAL MACHINE" --yesno "Start VM when completed?" 10 58); then
     echo -e "${GATEWAY}${BOLD}${DGN}Start VM when completed: ${BGN}yes${CL}"
diff --git a/vm/openwrt-vm.sh b/vm/openwrt-vm.sh
index 805d62bc5..2ad7de968 100644
--- a/vm/openwrt-vm.sh
+++ b/vm/openwrt-vm.sh
@@ -471,17 +471,24 @@ function advanced_settings() {
     fi
   done
 
-  if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
-    if [ -z $MTU1 ]; then
-      MTU1="Default"
-      MTU=""
+  while true; do
+    if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
+      if [ -z "$MTU1" ]; then
+        MTU1="Default"
+        MTU=""
+        echo -e "${DGN}Using Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      if [[ "$MTU1" =~ ^[0-9]+$ ]] && [ "$MTU1" -ge 576 ] && [ "$MTU1" -le 65520 ]; then
+        MTU=",mtu=$MTU1"
+        echo -e "${DGN}Using Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      whiptail --backtitle "Proxmox VE Helper Scripts" --title "INVALID INPUT" --msgbox "MTU Size must be a number between 576 and 65520, or leave blank for default." 8 58
     else
-      MTU=",mtu=$MTU1"
+      exit-script
     fi
-    echo -e "${DGN}Using Interface MTU Size: ${BGN}$MTU1${CL}"
-  else
-    exit-script
-  fi
+  done
 
   if (whiptail --backtitle "Proxmox VE Helper Scripts" --title "START VIRTUAL MACHINE" --yesno "Start VM when completed?" 10 58); then
     START_VM="yes"
diff --git a/vm/owncloud-vm.sh b/vm/owncloud-vm.sh
index 005dcf1f2..c9c9b0a1e 100644
--- a/vm/owncloud-vm.sh
+++ b/vm/owncloud-vm.sh
@@ -407,18 +407,24 @@ function advanced_settings() {
     fi
   done
 
-  if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
-    if [ -z $MTU1 ]; then
-      MTU1="Default"
-      MTU=""
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+  while true; do
+    if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
+      if [ -z "$MTU1" ]; then
+        MTU1="Default"
+        MTU=""
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      if [[ "$MTU1" =~ ^[0-9]+$ ]] && [ "$MTU1" -ge 576 ] && [ "$MTU1" -le 65520 ]; then
+        MTU=",mtu=$MTU1"
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      whiptail --backtitle "Proxmox VE Helper Scripts" --title "INVALID INPUT" --msgbox "MTU Size must be a number between 576 and 65520, or leave blank for default." 8 58
     else
-      MTU=",mtu=$MTU1"
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+      exit-script
     fi
-  else
-    exit-script
-  fi
+  done
 
   if (whiptail --backtitle "Proxmox VE Helper Scripts" --title "START VIRTUAL MACHINE" --yesno "Start VM when completed?" 10 58); then
     echo -e "${GATEWAY}${BOLD}${DGN}Start VM when completed: ${BGN}yes${CL}"
diff --git a/vm/pimox-haos-vm.sh b/vm/pimox-haos-vm.sh
index 8eff22ffb..75bfaadc1 100644
--- a/vm/pimox-haos-vm.sh
+++ b/vm/pimox-haos-vm.sh
@@ -339,17 +339,23 @@ function advanced_settings() {
     fi
     whiptail --backtitle "Proxmox VE Helper Scripts" --title "INVALID INPUT" --msgbox "VLAN must be a number between 1 and 4094, or leave blank for default." 8 58
   done
-  MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3)
-  exitstatus=$?
-  if [ $exitstatus = 0 ]; then
-    if [ -z $MTU1 ]; then
-      MTU1="Default" MTU=""
+  while true; do
+    MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3)
+    exitstatus=$?
+    if [ $exitstatus -ne 0 ]; then exit-script; fi
+    if [ -z "$MTU1" ]; then
+      MTU1="Default"
+      MTU=""
       echo -e "${DGN}Using Interface MTU Size: ${BGN}$MTU1${CL}"
-    else
+      break
+    fi
+    if [[ "$MTU1" =~ ^[0-9]+$ ]] && [ "$MTU1" -ge 576 ] && [ "$MTU1" -le 65520 ]; then
       MTU=",mtu=$MTU1"
       echo -e "${DGN}Using Interface MTU Size: ${BGN}$MTU1${CL}"
+      break
     fi
-  fi
+    whiptail --backtitle "Proxmox VE Helper Scripts" --title "INVALID INPUT" --msgbox "MTU Size must be a number between 576 and 65520, or leave blank for default." 8 58
+  done
   if (whiptail --backtitle "Proxmox VE Helper Scripts" --title "START VIRTUAL MACHINE" --yesno "Start VM when completed?" 10 58); then
     echo -e "${DGN}Start VM when completed: ${BGN}yes${CL}"
     START_VM="yes"
diff --git a/vm/truenas-vm.sh b/vm/truenas-vm.sh
index a0a19fae3..62c81cfeb 100644
--- a/vm/truenas-vm.sh
+++ b/vm/truenas-vm.sh
@@ -451,18 +451,24 @@ function advanced_settings() {
     fi
   done
 
-  if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
-    if [ -z $MTU1 ]; then
-      MTU1="Default"
-      MTU=""
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+  while true; do
+    if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
+      if [ -z "$MTU1" ]; then
+        MTU1="Default"
+        MTU=""
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      if [[ "$MTU1" =~ ^[0-9]+$ ]] && [ "$MTU1" -ge 576 ] && [ "$MTU1" -le 65520 ]; then
+        MTU=",mtu=$MTU1"
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      whiptail --backtitle "Proxmox VE Helper Scripts" --title "INVALID INPUT" --msgbox "MTU Size must be a number between 576 and 65520, or leave blank for default." 8 58
     else
-      MTU=",mtu=$MTU1"
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+      exit-script
     fi
-  else
-    exit-script
-  fi
+  done
 
   if (whiptail --backtitle "Proxmox VE Helper Scripts" --defaultno --title "IMPORT ONBOARD DISKS" --yesno "Would you like to import onboard disks?" 10 58); then
     echo -e "${DISK}${BOLD}${DGN}Import onboard disks: ${BGN}yes${CL}"
diff --git a/vm/ubuntu2204-vm.sh b/vm/ubuntu2204-vm.sh
index da3845597..8c30af1ef 100644
--- a/vm/ubuntu2204-vm.sh
+++ b/vm/ubuntu2204-vm.sh
@@ -403,18 +403,24 @@ function advanced_settings() {
     fi
   done
 
-  if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
-    if [ -z $MTU1 ]; then
-      MTU1="Default"
-      MTU=""
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+  while true; do
+    if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
+      if [ -z "$MTU1" ]; then
+        MTU1="Default"
+        MTU=""
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      if [[ "$MTU1" =~ ^[0-9]+$ ]] && [ "$MTU1" -ge 576 ] && [ "$MTU1" -le 65520 ]; then
+        MTU=",mtu=$MTU1"
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      whiptail --backtitle "Proxmox VE Helper Scripts" --title "INVALID INPUT" --msgbox "MTU Size must be a number between 576 and 65520, or leave blank for default." 8 58
     else
-      MTU=",mtu=$MTU1"
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+      exit-script
     fi
-  else
-    exit-script
-  fi
+  done
 
   if (whiptail --backtitle "Proxmox VE Helper Scripts" --title "START VIRTUAL MACHINE" --yesno "Start VM when completed?" 10 58); then
     echo -e "${GATEWAY}${BOLD}${DGN}Start VM when completed: ${BGN}yes${CL}"
diff --git a/vm/ubuntu2404-vm.sh b/vm/ubuntu2404-vm.sh
index f8d9d4fc7..d9b8c844d 100644
--- a/vm/ubuntu2404-vm.sh
+++ b/vm/ubuntu2404-vm.sh
@@ -406,18 +406,24 @@ function advanced_settings() {
     fi
   done
 
-  if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
-    if [ -z $MTU1 ]; then
-      MTU1="Default"
-      MTU=""
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+  while true; do
+    if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
+      if [ -z "$MTU1" ]; then
+        MTU1="Default"
+        MTU=""
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      if [[ "$MTU1" =~ ^[0-9]+$ ]] && [ "$MTU1" -ge 576 ] && [ "$MTU1" -le 65520 ]; then
+        MTU=",mtu=$MTU1"
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      whiptail --backtitle "Proxmox VE Helper Scripts" --title "INVALID INPUT" --msgbox "MTU Size must be a number between 576 and 65520, or leave blank for default." 8 58
     else
-      MTU=",mtu=$MTU1"
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+      exit-script
     fi
-  else
-    exit-script
-  fi
+  done
 
   if (whiptail --backtitle "Proxmox VE Helper Scripts" --title "START VIRTUAL MACHINE" --yesno "Start VM when completed?" 10 58); then
     echo -e "${GATEWAY}${BOLD}${DGN}Start VM when completed: ${BGN}yes${CL}"
diff --git a/vm/ubuntu2504-vm.sh b/vm/ubuntu2504-vm.sh
index aa71994c0..b4a11e955 100644
--- a/vm/ubuntu2504-vm.sh
+++ b/vm/ubuntu2504-vm.sh
@@ -405,18 +405,24 @@ function advanced_settings() {
     fi
   done
 
-  if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
-    if [ -z $MTU1 ]; then
-      MTU1="Default"
-      MTU=""
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+  while true; do
+    if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
+      if [ -z "$MTU1" ]; then
+        MTU1="Default"
+        MTU=""
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      if [[ "$MTU1" =~ ^[0-9]+$ ]] && [ "$MTU1" -ge 576 ] && [ "$MTU1" -le 65520 ]; then
+        MTU=",mtu=$MTU1"
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      whiptail --backtitle "Proxmox VE Helper Scripts" --title "INVALID INPUT" --msgbox "MTU Size must be a number between 576 and 65520, or leave blank for default." 8 58
     else
-      MTU=",mtu=$MTU1"
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+      exit-script
     fi
-  else
-    exit-script
-  fi
+  done
 
   if (whiptail --backtitle "Proxmox VE Helper Scripts" --title "START VIRTUAL MACHINE" --yesno "Start VM when completed?" 10 58); then
     echo -e "${GATEWAY}${BOLD}${DGN}Start VM when completed: ${BGN}yes${CL}"
diff --git a/vm/umbrel-os-vm.sh b/vm/umbrel-os-vm.sh
index 6fe728c72..443c1c77c 100644
--- a/vm/umbrel-os-vm.sh
+++ b/vm/umbrel-os-vm.sh
@@ -469,18 +469,24 @@ function advanced_settings() {
     fi
   done
 
-  if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
-    if [ -z $MTU1 ]; then
-      MTU1="Default"
-      MTU=""
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+  while true; do
+    if MTU1=$(whiptail --backtitle "Proxmox VE Helper Scripts" --inputbox "Set Interface MTU Size (leave blank for default)" 8 58 --title "MTU SIZE" --cancel-button Exit-Script 3>&1 1>&2 2>&3); then
+      if [ -z "$MTU1" ]; then
+        MTU1="Default"
+        MTU=""
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      if [[ "$MTU1" =~ ^[0-9]+$ ]] && [ "$MTU1" -ge 576 ] && [ "$MTU1" -le 65520 ]; then
+        MTU=",mtu=$MTU1"
+        echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+        break
+      fi
+      whiptail --backtitle "Proxmox VE Helper Scripts" --title "INVALID INPUT" --msgbox "MTU Size must be a number between 576 and 65520, or leave blank for default." 8 58
     else
-      MTU=",mtu=$MTU1"
-      echo -e "${DEFAULT}${BOLD}${DGN}Interface MTU Size: ${BGN}$MTU1${CL}"
+      exit-script
     fi
-  else
-    exit-script
-  fi
+  done
 
   if (whiptail --backtitle "Proxmox VE Helper Scripts" --title "START VIRTUAL MACHINE" --yesno "Start VM when completed?" 10 58); then
     echo -e "${GATEWAY}${BOLD}${DGN}Start VM when completed: ${BGN}yes${CL}"