I have tried ethernet cable with a known working ethernet cable - No Sucess
Reset the miner then also reset the modem then put the ethernet cable to another socket on the modem and then test it again - No Sucess
used a router - No Sucess
This seems like a control board went bad, I am afraid there isn't much that can be done about it.
If it has an Ip-report button you should try it, also if there is a way to Sdflash it that might fix it, meanwhile look for a spare control board, you can buy a used one for cheap.