We have had an issue where ether4 seems to stay on (RS) even when the cable is unplugged. When this happens, no data passes the port until we reboot the unit. Before 6.29.1, we had the same issue with ether3 as well as ether4. Is this a hardware fault? Sometimes, disabling/enabling the port fixes the problem but not always. Sometimes, plugging in a different device works but only for that device and nothing else.

Sounds like a hardware fault. A factory reset will rule out bad config.

I have reset to factory defaults a few times over a few versions and it still happens

I also done a netinstall and it still happens. I just noticed the port is showing R and the odd packet passing it without anything plugged in. It is not part of a bridge or network. Todays behavior allows me to plug in my PC and access the unit via MAC winbox. So it is very random it what it does.