Обновил прошивки на обоих устройствах. К сожалению проблема осталась. Вот журнал в момент потери связи:
[I] Dec 20 12:11:00 wmond: Core::Syslog: last message repeated 5 times.
[I] Dec 20 12:11:03 wmond: WifiMaster0/AccessPoint0: (MT7628) STA(d6:85:24:bf:5d:83) pairwise key handshaking timeout.
[I] Dec 20 12:11:03 wmond: WifiMaster0/AccessPoint0: (MT7628) STA(d6:85:24:bf:5d:83) had deauthenticated by AP (reason: PTK 4-way handshake timeout).
[W] Dec 20 12:14:22 kernel: Wi-Fi client: disconnected by peer
[I] Dec 20 12:14:22 kernel: br0: port 3(apcli0) entered disabled state
[I] Dec 20 12:14:24 kernel: Wi-Fi client: probe request: SSID=Keenetic, BSSID=50:ff:20:42:6e:4d
[I] Dec 20 12:14:24 kernel: Wi-Fi client: probe response: SSID=Keenetic, BSSID=50:ff:20:42:6e:4d, channel=9
[I] Dec 20 12:14:24 kernel: Wi-Fi client: associated
[I] Dec 20 12:14:24 kernel: br0: port 3(apcli0) entered blocking state
[I] Dec 20 12:14:24 kernel: br0: port 3(apcli0) entered forwarding state
[I] Dec 20 12:14:27 ndhcpc: Bridge0: received ACK for 192.168.100.5 from 192.168.100.1 lease 25200 sec.
[I] Dec 20 12:16:00 ndm: Network::InternetChecker: Internet access lost (status: 0x0001).
[I] Dec 20 12:16:10 ndm: Network::InternetChecker: Internet access detected.
[E] Dec 20 12:17:31 ndm: Core::Configurator: not found: "components/list".
[I] Dec 20 12:17:33 ndm: Network::InternetChecker: Internet access lost (status: 0x0001).