Symptom

AP disconnecting few seconds after joined WLC. ra_traces show "AP disconnect initiated. Reason: Max Retransmission to AP, Phase: Run" and WLC packet capture show packets transmitted by WLC receiving icmp unreachable

Conditions

Observed when MTU between AP and WLC is the max and WLC is able to receive join req with ip length 1469 and when MTU between WLC and AP is different and not the max and packets with ip length higher than 1466 are dropped

Workaround

Decrease the MTU between AP and WLC to match same MTU than between WLC and AP

Further Problem Description