Happy?

At one site, three channels is fine, but what do you suggest when houses/MDUs are right on top of each other and everyone has WiFi? Ch3 is Ch3, whether it's your network or your neighbor's and the signal from one can still interfere with the other.

Open your browser and enter the gateway IP address, then look at the wireless settings, It should indicate which channel it's using or set to Auto and if you click on the channel numbers, it should show the frequency.

I use a U-Verse gateway, by 2Wire and I have a Ubiquity router- if you have more than one to check, they probably use the same channels. Post the results and if needed, the rest of us could probably check ours and we can compare.

The FM tuner spec 'Alternate channel selectivity' is basically the same, but these use narrower bands and the slope at each end is a lot more steep. Leads to more crowding, but from what I have been told, almost all routers are set to 1, 6 or 11 out of the box. There's no problem using the others, as long as some nimrod doesn't come along later and jump on the one you're using because he thinks it will work better. At one house where I spend a good amount of time, I have counted more than 32 different SSIDs in the middle of the afternoon and at times, 7-8 of them may be stacked on one channel.