A friend of mine (also on Comcast) was having trouble with a netgear router being flakey and getting knocked off wireless periodically. Since she lived in an apartment complex and I saw many other wireless routers on the same channel I aimed to change the wireless channel. Dell laptop running Windows XP was slow but otherwise functional on a wireless connection.
Couldn't Get into admin on router
Password unknown. Since this was going to take a reset and she also had some problems with the laptop, I took the router aand laptop back to my place.
Setup the Router again and plugged into my Comcast modem.
Everything works now, wireless, wired etc. After a little work on the laptop things are working nicely. Power cycled and everything is still good.
Brought everything back, plugged into her Comcast modem - Problems!!!
Laptop connects wirelessly, or via ethernet, however no internet access. Browser acted as if there was no DNS however an ipconfig /all showed dns assignements.
Unplugged router and plugged laptop directly into the cable modem with an ethernet cable... everything works!
I'm stumped. Have never seen anything like this before. I have the feeling i'm missing something really simple and stupid here but what? Is there some issue with the modem that makes it not want to talk to the router?
Yes. If you are using a telephony type modem that has a built in backup battery then just removing the A.C. power will not powercycle it. You need to use the recessed reset button on the rear. You'll need something like a bent paper clip or the tip of a pen to do so. Alternately you can both remove the battery and the A.C. power to reset it.
Glad that worked for you ! It's not that it is "sensitive". The modem stores the hardware MAC (Media Access Control) address of the last device that was directly connected to it. It is deliberate that it has a MAC address cache that can only be cleared via a powercycle operation. CC supplies only a single IP address to a residential connection.