Move SD from Pi400 to Pi4 - does not show on network

Hi

I have a Pi4 32bit OS with OMV6 on SD with data on SSD.

Changing to OMV7 on 64bit

Used a spare Pi400 to setup OMV7, using new SD card and cloned SSD.

Got all my setup correct and functioning 100%

Now want to move the 64bit OS OMV7 SD card from the test Pi400, to my main Pi4

Pi4 is headless.

SD in to Pi4, and no IP address appears in the router ARP table.

Downloaded Angry IP and scanned full IP range and nothing listed.

Moved the SD card BACK to the Pi400, and shows up perfectly.

Advice please.

Quote from Soma

You need to connect the Pi4 to a monitor and keyboard and run omv-firstaid to reconfigure the ethernet.

No other way.

Thank You. was hoping for a way without needing a monitor, but it worked and was painless.

Thank You