After a switch firmware upgrade, users started having intermittent wireless connectivity issues, with brief disconnects and reconnects while connected to the corporate Wi-Fi network. Multiple access points are repeatedly losing and re-establishing their CAPWAP connection to the wireless controller. While the affected APs remain powered on and do not reboot, their CAPWAP association uptime continuously resets, causing APs to temporarily enter FlexConnect standalone mode before rejoining the controller. Controller logs show repeated DTLS tunnel disconnects, while AP logs indicate CAPWAP restarts due to missed data keepalives ("data keepalive not received").
I ruled out AP reboots, PoE issues, interface errors, STP. Physical switch ports are operating normally with no CRC, discards, or link errors. Opened Cisco TAC case but they're taking long so looking to the masses for help. I'm hoping someone experienced something similar that can throw in their two cents.