Last week I had 3 locations lose connection to our controller. We have 11 locations.
The APs get IP, they get the controller discovery address.
I can ping from the controller to the APs, i can SSH from a host server to the APs.
I can ping from the APs to the Controller.
I can see in my firewall the traffic from the APs going through each firewall and the VPN.
I can see traffic from the controller going through each firewall and the VPN.
On the AP, it normally says Communicating with Controller for a long time.
Then switches to something about Missing the last IP hop, then it reboots and tries again.
On the controller under Netstat I see all of my Down APs with this message
tcp 0 0 192.168.7.123:33333 192.168.11.45:54782 FIN_WAIT2
Everything was working perfectly fine for years. There hasn't been any changes to the firewalls or the controller.
The controller and APs were running 3.7.1, I have since upgraded the controlled to 4.1.0 hoping maybe that would help resolve this.
I have reset each model of AP.
The APs are mix of 1920 and 2020.
heh worth a shot.. thinking back i've seen something like this before, did you try rebooting the firewall?