I switched two TL-WR1043ND that were still running 10.03 to 12.09 this weekend.
It seems the wireless is now much less reliable than before.
Previously it would run without issues for months on end.
Now it seems like on one of the devices regularily loses it's wireless clients,
which looks like this in the log:
Jan 14 02:10:13 untermdach daemon.notice netifd: mgmt (664): Sending discover...
Jan 14 02:10:13 untermdach daemon.notice netifd: mgmt (664): Sending select for 192.168.254.186...
Jan 14 02:10:13 untermdach daemon.notice netifd: mgmt (664): Lease of 192.168.254.186 obtained, lease time 43200
Jan 14 02:10:13 untermdach daemon.notice netifd: Interface 'mgmt' is now up
[...]
Jan 14 02:10:39 untermdach user.info sysinit: setting up led USB
Jan 14 02:10:39 untermdach user.info sysinit: setting up led WLAN
Jan 14 02:11:08 untermdach daemon.info hostapd: wlan0: STA 4c:60:de:aa:aa:aa IEEE 802.11: authenticated
Jan 14 02:11:08 untermdach daemon.info hostapd: wlan0: STA 4c:60:de:aa:aa:aa IEEE 802.11: associated (aid 1)
Jan 14 02:11:08 untermdach daemon.info hostapd: wlan0: STA 4c:60:de:aa:aa:aa WPA: pairwise key handshake completed (RSN)
Jan 14 02:11:09 untermdach daemon.info hostapd: wlan0-1: STA d0:e7:82:bb:bb:bb IEEE 802.11: authenticated
Jan 14 02:11:09 untermdach daemon.info hostapd: wlan0-1: STA d0:e7:82:bb:bb:bb IEEE 802.11: associated (aid 1)
Jan 14 02:11:09 untermdach daemon.info hostapd: wlan0-1: STA d0:e7:82:bb:bb:bb WPA: pairwise key handshake completed (RSN)
Jan 14 02:15:26 untermdach daemon.info hostapd: wlan0-1: STA 00:04:20:cc:cc:cc IEEE 802.11: Station tried to associate before authentication (aid=-1 flags=0x0)
Jan 14 02:15:26 untermdach daemon.info hostapd: wlan0-1: STA 00:04:20:cc:cc:cc IEEE 802.11: authenticated
Jan 14 02:15:26 untermdach daemon.info hostapd: wlan0-1: STA 00:04:20:cc:cc:cc IEEE 802.11: associated (aid 2)
[...]
Jan 14 05:06:26 untermdach daemon.info hostapd: wlan0-1: STA 00:04:20:cc:cc:cc IEEE 802.11: disassociated due to inactivity
Jan 14 05:06:27 untermdach daemon.info hostapd: wlan0-1: STA 00:04:20:cc:cc:cc IEEE 802.11: deauthenticated due to inactivity (timer DEAUTH/REMOVE)
Jan 14 05:06:56 untermdach daemon.info hostapd: wlan0: STA 4c:60:de:aa:aa:aa IEEE 802.11: disassociated due to inactivity
Jan 14 05:06:57 untermdach daemon.info hostapd: wlan0: STA 4c:60:de:aa:aa:aa IEEE 802.11: deauthenticated due to inactivity (timer DEAUTH/REMOVE)
Jan 14 05:06:57 untermdach daemon.info hostapd: wlan0-1: STA d0:e7:82:bb:bb:bb IEEE 802.11: disassociated due to inactivity
Jan 14 05:06:58 untermdach daemon.info hostapd: wlan0-1: STA d0:e7:82:bb:bb:bb IEEE 802.11: deauthenticated due to inactivity (timer DEAUTH/REMOVE)
So after 3 hours suddenly all stations timed out.
Even more interestingly when I do a wireless scan on the web UI, immediately all stations reconnect:
an 14 05:06:57 untermdach daemon.info hostapd: wlan0-1: STA d0:e7:82:bb:bb:bb IEEE 802.11: disassociated due to inactivity
Jan 14 05:06:58 untermdach daemon.info hostapd: wlan0-1: STA d0:e7:82:bb:bb:bb IEEE 802.11: deauthenticated due to inactivity (timer DEAUTH/REMOVE)
Jan 14 08:10:31 untermdach daemon.notice netifd: mgmt (664): Sending renew...
Jan 14 08:10:31 untermdach daemon.notice netifd: mgmt (664): Lease of 192.168.254.186 obtained, lease time 43200
Jan 14 08:24:35 untermdach authpriv.notice dropbear[6950]: Pubkey auth succeeded for 'root' with [...] from myip:57370
Jan 14 08:28:15 untermdach daemon.info hostapd: wlan0-1: STA d0:e7:82:bb:bb:bb IEEE 802.11: authenticated
Jan 14 08:28:15 untermdach daemon.info hostapd: wlan0-1: STA d0:e7:82:bb:bb:bb IEEE 802.11: associated (aid 1)
Jan 14 08:28:15 untermdach daemon.info hostapd: wlan0-1: STA d0:e7:82:bb:bb:bb WPA: pairwise key handshake completed (RSN)
Jan 14 08:28:26 untermdach daemon.info hostapd: wlan0-1: STA 30:85:a9:dd:dd:dd IEEE 802.11: authenticated
Jan 14 08:28:26 untermdach daemon.info hostapd: wlan0-1: STA 30:85:a9:dd:dd:dd IEEE 802.11: associated (aid 2)
Jan 14 08:28:26 untermdach daemon.info hostapd: wlan0-1: STA 30:85:a9:dd:dd:dd WPA: pairwise key handshake completed (RSN)
Jan 14 08:28:31 untermdach daemon.info hostapd: wlan0-1: STA 00:04:20:cc:cc:cc IEEE 802.11: Station tried to associate before authentication (aid=-1 flags=0x0)
Jan 14 08:28:31 untermdach daemon.info hostapd: wlan0-1: STA 00:04:20:cc:cc:cc IEEE 802.11: authenticated
Jan 14 08:28:31 untermdach daemon.info hostapd: wlan0-1: STA 00:04:20:cc:cc:cc IEEE 802.11: associated (aid 3)
Jan 14 08:28:32 untermdach daemon.info hostapd: wlan0-1: STA 00:04:20:cc:cc:cc WPA: pairwise key handshake completed (RSN)
Jan 14 08:28:47 untermdach daemon.info hostapd: wlan0: STA 4c:60:de:aa:aa:aa IEEE 802.11: authenticated
Jan 14 08:28:47 untermdach daemon.info hostapd: wlan0: STA 4c:60:de:aa:aa:aa IEEE 802.11: associated (aid 1)
Jan 14 08:28:47 untermdach daemon.info hostapd: wlan0: STA 4c:60:de:aa:aa:aa WPA: pairwise key handshake completed (RSN)
Jan 14 08:30:20 untermdach daemon.info hostapd: wlan0: STA 4c:60:de:aa:aa:aa WPA: group key handshake completed (RSN)
I haven't observed this with 10.03.
For now I'll try scripting a regular wireless scan and see if that helps.
I'll probably also try Barrier Breaker in a few days to see if it's fixed there.