The router really is where the change would be needed, I think.
WiFi channel may be an obscure setting on some handhelds. But *if* the WiFi channel might not be changed on them, then it must be set to a standard channel value, and the selection on the router must have changed, and thus the channel on the router needs be changed back.
Open a web browser on your computer.
Enter the IP address of your local router in the Address field and press the RETURN key.
You should get a popup prompt for username and password. This is normal when accessing a router's settings... for username, enter
and for the password... whatever the admin password ***** ***** to. If it is set to a default value, such as
or just a blank, no characters... then that explains your problem: with a default password, anyone within range of your router (several hundred yards theoretically) could access the router's settings and change them. In any case, log in to
and whatever password ***** have, or that works, then go into the WiFi settings, note the channel setting, and set it to 11 (or 6 perhaps.) Those are most likely to work best and be fastest, and if the setting is anything else, it has most likely been meddled with.
IF that restores your wireless communications with all devices, once you have set it that way and Saved the changed setting, please go back to the admin setup of your router, and change the password (the 'admin' password, NOT the wireless password ***** passphrase or encryption key... the distinction is important.) That way your router settings cannot be changed by any stranger.