Thanks, but I don't think you can "turn off" QoS... it's just a matter of setting rules which can, if you choose, throttle or prioritise traffic.. and this I haven't yet done. Albeit, having QoS capabilities was one of the reasons for getting the Billion.
However, one thing occurs to me, noting the approximately hourly frequency with which the disconnections occur.. The wireless capability of the router does include one parameter with an hourly periodicity - namely the Group Key Renewal (which is a function of WPA security). I'm wondering whether there is any chance that the internal reconfiguring occasioned by this wireless function is somehow impacting the way the router responds to ethernet connections, perhaps just dropping a packet or two.. Clearly, that shouldn't happen - and I'm perhaps clutching at straws - but it would be somewhat consistent with my experience that the non-wireless Voyager is fine, but both wireless-enabled routers are problematic..
Thing to do is experiment with that parameter, I guess, or with a different (non-WPA) security mode, and see what happens.
Thanks again..