No network configuration possible

Hello everyone,

My server went offline and checking I saw that the network interface is no longer configured. I tried to reconfigure the network interface with omv-firstaid, but both with the manual IP configuration and with DHCP it is not possible to restore the functionality of the network interface, even if the configuration always completes successfully. The server remains offline, it does not see the other hosts in the LAN and is not visible to the other hosts present in the LAN. I changed various network cables, I changed ports on the switch and all other possible attempts, nothing to do. I thought that by configuring the IP manually I would have been able to at least ping the router, but nothing. What can I do to restore the functionality of the network? Thanks

Um... um...

I had connected a backup router to the switch instead of the main router following a fiber optic downtime and then, once the downtime was resolved, I forgot to swap them again. When connecting with wi-fi I didn't notice anything, while the devices connected to the switch could no longer work... It's my memory's fault, everything else is alive and well and works as usual. I apologize for the mix-up, thanks for your attention.