@mpaulauskas were you able to resolve this issue? I’m having the same experience with a Model A 3.4, which has worked fine connected to an 8-port switch module in a Cisco 1941W for five years but doesn’t work on a 2960S. I have an A3 (wired) at work, which works on a 2960-X (with about 25m of structured cable) and also a 6509 (1m patch lead).

The interface comes up for ~15 seconds and then goes down and, as you observed, no MAC address appears in the CAM table. The Ethernet controller in the A seems to lock up at that point, since leaving it powered and connecting it back to the 1941 results in the interface still not coming up. Power-cycling the A returns it to normal operation.

Interestingly, if the A is booted whilst connected to the 1941 and I re-patch it to the 2960S it works fine. Booting it whilst not connected to anything results in a locked-up Ethernet controller after ~15 seconds, which requires power-cycling to rectify.

The A is the only thing left connected to the 1941, which is being retired since I have a new firewall, it’s old, doesn’t have enough ports, and also no longer need the ADSL capability. I have a wireless A3 at home, as well, so I may just end up retiring the Model A.