F2-421 plugged but unresponsive

[MrLeonida]

Hello! I have been an owner of an F2-421 for about 2 months.
Since yesterday morning I can no longer access the NAS, either via url or via desktop app. I tried to restart the NAS, connect the ethernet cable to a different port on the router and try the TOS re-installation procedure: nothing to do, the problem is that the device, although connected and with all the green LEDs, is not on the network (no IP).
Any suggestions?

[TMSupport]

It is recommended to check whether the computer and nas are in the same network segment

[MrLeonida]

Yes, confirmed they are on the same network.
Also, already the router can't see the NAS connected directly to ethernet (it does not appear in the web app of the router among the connected devices), unlike other devices that I tried to connect to the same port.
Has the NAS network card been blown?

[TMroy]

Please shutdown the device, pull your all drives out from your tnas, power on again without hard drives. Search the device in the network with the TNAS PC app on your computer. and you tell if the device can be found.