OpenWrt "sta" mode clients timeout (fixed by rebooting AP)

I have a few OpenWRT (ath9k) 19.07.x devices in "sta" mode that stopped authenticating :

daemon.notice wpa_supplicant[1465]: wlan0: CTRL-EVENT-SSID-REENABLED id=0 ssid="db120"
daemon.notice wpa_supplicant[1465]: wlan0: SME: Trying to authenticate with a0:f3:c1:xx:yy:zz (SSID='db120' freq=2462 MHz) kernel: [  595.438668] wlan0: authenticate with a0:f3:c1:xx:yy:zz kernel: [  595.454667] wlan0: send auth to a0:f3:c1:xx:yy:zz (try 1/3) kernel: [  595.610047] wlan0: send auth to a0:f3:c1:xx:yy:zz (try 2/3) kernel: [  595.730054] wlan0: send auth to a0:f3:c1:xx:yy:zz (try 3/3) kernel: [  595.840044] wlan0: authentication with a0:f3:c1:xx:yy:zz timed out

daemon.notice wpa_supplicant[1465]: wlan0: CTRL-EVENT-SSID-TEMP-DISABLED id=0 ssid="db120" auth_failures=10 duration=90 reason=CONN_FAILED

All my Fedora "sta" mode devices auth OK (ath9k & iwl7265).

The "access point" is running OpenWRT (ath79) 19.07.7. It's was up for 17 days. I don't see any info in logread to explain the auth time outs. When I reboot the access point, all the OpenWRT "sta" mode clients authenticate. I did not see this behavior in previous versions of OpenWRT.

I would guess this is some kind of hostapd bug (wpad-basic 2019-08-08-ca8c2bd2-5).

Are there any debug flags I could use to isolate this. Or workarounds ? I suppose I could reboot the AP every 17 days or revert to OpenWRT 19.07.5 ...

Now that I think about it ... the AP is "dual band", so it's likely that all there was a problem w/ the 2.4 GHz radio / hostapd and the other "sta" clients (Fedora & Android) were using 5 GHz ...

TBH I'm facing similar behaviour, that affects both my OpenWRT client and regular devices (phones). It's not very apparent since I have 2 APs in the apartment (main WRT3200ACM and wired R6220) but the 3rd AP/repeater suffers and it's my work environment so it's the most apparent there.

It is exactly like you are saying, every now and then my phone will fail authentication and my repeater will disconnect, only to connect flawlessly after reboot. This was happening both with 21.02 and 23.05.rc4 on AP, typical workaround (opkg remove kmod-mwifiex-sdio) applied.
My affected band seems to be 5GHz actually.