I moved the UNRAID Server network cable to a different router port without power down the server & the router. Right after the cable move, Server's Ethernet port LEDs went blank. I rebooted the server and router. Everything is working except the Server Ethernet port LEDs still blank with “dev eth0 linkdown” error message. I can PING the port etc. and it seems like it is still working. Can someone please tell me if there is way to fix this or I should get a new Ethernet NIC?  Thanks!

 

Supermicro C2SEA with UNRAID 6.3.5
 

What happened to the lights on the router end of the CAT5 cable which connects to your server?

 

You should also get a the diagnostics file and post it up with your next reply.   Either   ( 'Tools'   >>  'Diagnostics'    ) or   type diagnostics on the command line and that will write the file to the logs folder/directory on your flash Drive. 

First of all, thank you for answering my SOS. 

 

I don't know how you do it.  Some how you knew it was cable problem "end of the cat5 cable".  Anyway, I moved the router next to the server, connected the router to the server with a three feet cat5 cable.  Power on, within 30 sec. the Ethernet lights came back on.  Since I cannot reproduce the problem, I can only assume it was the long cat7 cable caused the problem.  Once again, thank you very very much.

 

cables are usually the first thing to troubleshoot.  cheapest solutions first