I see the workaround is to disable the 5GHz band on the router. For users of the newer streamers who might be seeing the same problem, you might try forcing the streamer onto 5GHz instead by configuration in the router.
I know this is possible on a Virgin hub3 - I have my ND5XS2 set up this way - but if anyone with a BT hub knows it’s NOT possible on BT shout and I’ll delete this post.
Oh dear, that’s not great.
Disabling 5GHz on the router is the temporary fix recommended by BT until they can fix this by firmware update. It only affects streamers on WiFi so an Ethernet cable would work fine.
(This is not a Naim specific problem, any devices that try to talk to each other wirelessly over your network will be affected if they happen to be on a different frequency.)