to change the channel you need to access the router setup, usually through a browser interface (like www.routerlogin.net
or an ip you enter in the address line of your router). It's not an OS setting, it's a network hardware thing.
The channel is normally chosen automatically, but with other wifi networks in close range, that may not always work as intended, because the other routers will also try to find the best channel. Choose the highest or lowest channel and see if it helps. If it won't be stable, walk through the channels.
It happened to me exactly as you described it and changing the channel was the solution.
Please report if it worked.