I think I'm going to have to give up with the 5GHz, and just accept single-channel operation... even with our Q and miniboxes powered off there's still next door's operating across the lower channels
However, the stock fw in the zyx appears more stable than the plusnet version it shipped with, and still syncs so much faster than the TT hub, so I'm still overall winning

Thanks again to all who've helped out on this
