[cortexman]

I don't believe my specific router/firmware versions are relevant for this problem, but if needed I will post.

The basic issue is that the laptop running Snow Leopard connected via wifi at first gets a dynamic IP address provided by the router, but a short time later (2-3 seconds) this IP address blinks and changes into the IP address of my cable modem. This laptop can always connect to the internet. The desktop on the other hand always gets a dynamic IP from the router, and it doesn't blink, and it never connects to the internet.

The only difference between the two (that I have discovered) is the DNS settings - somehow the laptop gets a couple of comcast DNS servers set, in addition to a DNS search domain. The desktop gets none. I've added the DNS settings the laptop somehow gets to those of the desktop, but it never works.

Since I know that the cable modem is functioning properly, that narrows the problem to either my router or one of the computers. Some strange setting on my computers that I am unaware of aside it appears to be something in the router. The router has default settings with the exception of wifi authentication and SSID.

Totally lost at this point.

- Brian

[crashfly]

While you might not believe the router & firmware is relevant to the problem, it would still be a good idea to post them anyway. Now, on to the problem ...

You did not mention how your router is set up (what functions it provides to the network [e.g. gateway]). In addition, do you have your computers/cable modem plugged into the correct ports?

And last but not least, have you read the "Peacock" thread to go through possible problems on your connection (and to check if you are running a supported build)?

[DoesItMatter]

I would see this once or twice while I had my router rebooting

I used to run my main router - WHR-G300N

Occasionaly, during reboots, the wan port would be 'switched' and one of my PC's
would get the external IP from my ISP, instead of the router getting the external IP.

Best way you can test is the following

Turn off wireless connections (i.e. turn off laptop)
Unplug any lan connects to router, just leave the WAN -> cablemodem plugged in

Power-cycle cable modem and power-cycle router - leave them for about 5 minutes

Plug in the LAN connect to your desktop, access the GUI, and see if you can get internet

THEN go ahead and turn on the laptop and see what happens.

IF for some reason your laptop hijacks the external IP, re-flash the router.

30-30-30 that thing (unless its the models that cannot do the 30-30-30)
then re-flash a good recommended build (not 13064), and then try test above once again.

[ReadtheAnnouncements!]

My bet is that you have two dhcp servers on the same subnet. Read the wiki on linking routers. Simple solution is to plug the modem into the wan port of the router and set the router LAN IP to 192.168.2.1