We have the link aggregation supported in the release 5.9.2.0 on APs with two gig interfaces. You may upgrade the firmware and use the feature if required.
usually, people may use the second interface for a wired client or service.
Either you open up a support case, for a speedy resolution
or do the following;
1. On both APs enable "logging console debugging" (Assume you do SSH to the devices) and commit
2. On both SSH consoles execute the following action commands
logging...
1. Make sure both AP and VC are on same VLAN
2. If NOT, configure "controller host " on AP's profile/Device context
At this point they should form mint neighbor-ship. And "show mint known adopters" on AP should show VC's mint-id.
You may also try "m...