In this modem, does the QoS functionality described in the web ui make any sense or even apply if the the device is in modem-only ‘bridged’ mode? It would have to snoop on the PPP and PPPoE packets’ payload / contents then, to be able to apply ethernet L2 QoS and or L3 IP QoS-based functions?
The ISP AA applies some customisation to the config which is called QoS, but I don't know if this is just a mistake, an unintended commonality with the settings they use when they are programming the devices for shipping as routers not modems.