In the ZHA integration configuration it is possible to change the Zigbee channel. Tap the pencil icon next to the channel (NOT “Migrate Radio”). There is a warning about channel migration being experimental but if all you have is Hue bulbs I wouldn’t worry too much (my bulbs are Tradfris, and they were fine at least). I had to do this initially to get reliable coverage, and everything has been solid since.

The channel change seemed to make switching lights on/off faster but not more reliable. One or two bulbs still don’t respond (ironically even one that’s closest to the ConBee)

I’ve tried using the ConBee II on a USB extension cord and it wasn’t much better.

+ I don’t like having another cable thrown around the living room. I thought the whole point of Zigbee was that the devices create a mesh and so coverage wouldn’t be much of an issue, no? (maybe I’m mistaken?)

I’ll try the switching the channel to see if that improves things and report back.