This doesn't sound like a problem with the router. It sounds more to me like you had a problem with your cable service.
I have Comcast also and assume you have the same basic setup that I do: coaxial cable from the wall (just like one you'd plug into a TV) to a cable modem, then ethernet cable out from the modem to a router. I have an ethernet cable from the router to my desktop and use wireless for a couple of laptops and an Xbox 360.
I occasionally have problems with my cable modem dropping its connection to the Comcast network. I found a way to check the incoming signal strength through the modem on DSL Reports
-- can't remember exactly how I did it -- and my signal level is on the low end of acceptable which is what I assume causes this to happen. When it does, my hardwired and wireless computers still see the router fine and can transfer files to each other, but they can't access the internet.
I'm guessing you fixed your problem by power cycling the modem.
If you have this problem again, I would (in order):
- Turn off the computer and unplug the power to the router and the modem. It's a good idea to wait about 1 minute before plugging anything back in but not always necessary.
- Plug the modem back in and wait for it to connect to the network. You should have some status LED's on the modem which will let you know when it's connected. It usually takes mine about 15-30 seconds to connect.
- Plug the router back in and wait for it to connect to the modem. Again, you should have some status LED's on the router to let you know when it's finished.
- Then turn the computer back on and see if everything works.
Hopefully you won't need to test this out, but let me know if it doesn't work.