Here's an interesting one. I configured a simple mesh link for customer with 2 x IAP104. I can't ping either IAP or the VC address, but the customer assures me that it is working. Interestingly, I am able to ping the switch at the remote end.
There is an entry in Airwave, so they poppped up in there briefly at some point, but showing as down now.
Not sure what to do given it appears to be working, but I need to be able to manage it.