A friend recently bought one of these and we have been trying to get it working ever since.......

I have tried everything I can think of to get it to communicate with a PC and read dozens of posts about people having the same problem.

The most obivious things are:
Different pluggins ( including the one for the later EC500 )
Multiple IP addresses ( always used the Netmask )
Different Ethernet cables
With and without a Router ( removed the IP when testing the router.
Disabled the firewall
Ran Winfdoes Diagnostics. Best clue I got was 'IP address was not configured correctly" No idea why, or how.

Most of the tales of woe were from around 2017, some a little later.

Best I get is 'connected' led and Sent packets, but No recieved traffic from Novusun.

I know the answer already, but here goes:

Before I hurl this thing against a brick wall, Has anything significantly changed that will now allow this to now work properly in 2023?

We are looking at getting a UC300ETH to replace it.

Steve