I was trying to say is use another port from the switch (try swapping the ports used by the TV and your PC).What do you mean by “another source port”?
By the way, I’ll mention that the TV is not connected directly to the router. It is connected to a multi port switch, which is then bridged to the router over a MOCA connection. From the TV’s perspective though it would think it’s connected to the router.
A PC is connected to that same switch.
One thing I have noticed with the TV is that it frequently makes DHCP requests. It always has. I don’t know what would happen if the router didn’t respond or responded “oddly”. That’s one of the reasons I set up a static DHCP as once I saw the router show 2 different IP addresses for the TV (wifi is disabled).
As a last resort, you can always go back to the 384.16 (temporarily say for a 1 or 2 weeks) and see if your issue returns.