On an RB2011UAS ROS 6.3, I have noticed odd behaviour with an RJ45 loopback plug.
While testing the 100Mbit ports, they seem to ignore it - don’t come up active when I plug it in.
If I connect a switch to the port first, and then the loopback plug, it comes up for the switch, down when I take the cable out and then back up for then loopback.
It then behaves as I would expect - active when inserted - until the port has been disabled and re-enabled.
Then it ignores the loopback again.
Same in ether auto negotiation or set to 100/full.
What is going on ?