Symptom
AP3800 disconnecting continuosly from 9800 running 16.12.X, 17.1.1s or 17.2.1
AP outputs of debug capwap client event/error/pmtu shows the following messages:
Kick Starting Dynamic Path MTU Discovery
PMTU: Sending MTU update to WLC: dcb->mtu
CAPWAP HW tunnel params changed, DELETING the existing
(...)
Going to restart CAPWAP (reason : data keepalive not received)...
Conditions
Observed in flexconnect APs when ap link-encryption is configured and AP capwap MTU is lower than maximum (1485)
Workaround
Remove ap link-encryption
