Can't connect to the Internet, local connection only??

Have you tried setting a static IP to it with the "static DHCP" feature of most routers? Might force it to work.

Also with the "channel" thing think of it as different roads to take... congested roads cause slowdowns and interferrence, changing it is like taking another route.

Changing it to one that's not congested helps greatly.

Also some routers have a "band" option like "b/g/n" "g/n" and "n only" modes and your laptop might only connect if the "band" is configured to "g/n" or "b/g/n". I have the same problem on my amped rta15 router. I have an older HP media center PC and a motorola barcode scanner that only connect when I have it configured to "b/g/n"

Of course I get around that and have a network on my meraki MR12 access point and they connect fine to that and I have the rta15 at N only.