The DrayTek Vigor has this inexplicable habit of sometimes reconfiguring itself to turn off all wireless comms. The laptops don't much notice because they fall-over to the Belkin AP. Our old Squeezebox Classics do the same.
However, our Squeezebox Touch refused to play along. Studying the Touch was highly instructive. My SSID is something like "Home LAN". And all laptops always saw "Home LAN, Home LAN, Home, ...". Not the Touch. The Touch saw "Home LAN, Home?LAN, Home, ..." where only "Home?LAN" was available (the other two having gone down with the DrayTek). This made me pause and go into the SSID configuration screen of the Belkin. Sure enough, it said there "Home LAN" but, sod it, I simply re-typed the " ", rebooted and watched in amazement.
I have no idea how I entered the original SSID - probably cut+paste from the Vigor's configuration screen. And it is only the Touch that objected to what was clearly not a space but which appeared on EVERY OTHER DEVICE - including the network sniffer I used the other day - as just a space.