Trying to diagnose this problem, I read something about the channels wifi routers use, and that there's some kind of "overlap" which extends two channels up and two channels down and can cause some "interference". If one is set to channel 1, the overlap extends up to channel 3, and if another is set to channel 6, the overlap extends down to channel 4, so there's no overlap. The article suggested using channels 1, 6 and 11, as there's no overlap between these three channels.
I downloaded the Wifi Analyzer app for my mobile, and noticed that:
(1) I have a couple of neighbours using channel 1, and one using channel 11. The strength of signal on these is reasonably high.
(2) There is another neighbour using channel 10. Looking at the network name I can work out who this one belongs to. It's a few houses away. The signal just pops up occasionally, and is quite weak.
(3) My router was using channel 9. Why 9? No idea. I didn't set that.
I figured I would reset mine to 6 - no overlap with the strong signals, some overlap with the intermittent weak signal, might help with the dropouts.
So I poked around in the Thomson Gateway interface, found the relevant configuration option, and changed the channel to 6. Wifi Analyzer now shows the signal on channel 6 (stronger than it was on 10, so that's good), but no devices will connect to it now - not my HP Windows desktop, Android phone or the wife's iPad. I’ve restarted the Thomson, but that didn’t help.
Is there something I need to reset on each device? Do I need to “forget” the network, and set it up from scratch on each device? Any ideas?