pfSense

Just rebooted and WiFi is back again. I still get the stuck beacon message in the system log, but less frequently than while the WiFi was down (at that time I got some 4 messages per second, now the rate of messages varies, 1 message per second on average, with gaps up to 5 seconds).

Update: after the last loss of WiFi I just left everything alone and the next morning I noticed the WiFi was back (though later the same on-off game started over again).

Therefore I can't tell for sure if the WiFi is ever gone for good or if all failures are just sporadic in nature and the WiFi eventually recovers by itself.

In any case, this behavior is rendering the WiFi adapter completely unreliable and thus unusable.

I have downgraded to 2.1.4 (i.e. reinstalled 2.1.4 from scratch and restored config). I noticed that after the first few reboots the WiFi adapter was not detected at all, after a few reboots it was there again and I could configure it.

I'll watch the setup for a few days and will post if going back to 2.1.4 improves the situation.

I had the same issue, with nearly the same setup (APU 1D4 engine).

What really helped me, was to set the Wireless Standard to 802.11b. Unfortunately you're now limited to 11Mbit/s.

The other wireless settings are the same as yours.

I have a similar issue with an "APU3 C2" board since upgrading pfSense from v2.4.5p1 (FreeBSD 11.3-STABLE) to v2.5.0 (FreeBSD 12.2-STABLE)

Symptoms
WiFi lost after some working hours.

Workaround
Restart pfSense each time the issue appears.

pfSense
2.5.0-RELEASE (amd64)
built on Tue Feb 16 08:56:29 EST 2021
FreeBSD 12.2-STABLE

Hardware
- PC Engines APU3C2 board
- Compex WLE200NX wireless card (Atheros AR9280 chipset)

• Common wireless configuration
  • Persist common settings: unchecked
  • Standard: 802.11ng
  • 802.11g OFDM Protection Mode: Off
  • Channel: 11b/g/n-6
  • Channel width: Auto
  • Distance setting (meters): blank

• Network-specific wireless configuration
  • Mode: Access point
  • Minimum wireless standard: Any
  • Allow intra-BSS communication: Yes
  • Enable WME: Yes
  • Enable Hide SSID: No

• WPA
  • Enable : checked
  • WPA Mode: WPA2
  • WPA Key Management Mode: Pre-Shared Key (PSK)
  • WPA Pairwise: AES
  • Group Key Rotation: 60
  • Group Master Key Regeneration: 3600
  • Strict Key Regeneration: unchecked

• SysLog - System - General
  "ath0: stuck beacon; resetting (bmiss count 4)" twice per second
• SysLog - System - WireLess
  "ath0_wlan0: WPA rekeying GTK" every minute
  "ath0_wlan0: WPA GMK rekeyd" every hour

MAJ 2021-04-12
I can see these new improvements with FreeBSD v12.2 :
"Updates to the wireless networking stack and various drivers have been introduced to provide better 802.11n and 802.11ac support."
from https://www.freebsd.org/releases/12.2R/announce/