If your router supports it, try doing a MAC address clone. If it doesn't, go with MetalMikester's suggestion of checking for a firmware update. If those both fail, and you are confident with your computer's firewall, plug directly into the modem and test the speeds:
- If your computer gets the same IP address* as the router had, and the speed is faster, then your problem is the router.
- If your computer gets the same address and the speed is the same, then your ISP could be throttling your connection down or the modem could be bad.
- If your computer gets a different IP and it's faster, then it could be the router, but it also could be your ISP throttling.
- If your computer gets a different IP and it's slower, then there may be something wrong with the modem itself.
There are more possibilities than this, but this gives you a basic guideline of the simple solutions.
One caveat is that some ISP's (Charter does this, for one) will snapshot the MAC address of the first machine to connect to the internet, whether it is a computer or router. This becomes a problem when diagnosing connections, because any other MAC addresses to connect on the line will be shutout from getting a connection. (This happened to my Father-In-Law. Luckily he had a WRT54GL running DD-WRT and was able to clone the MAC of his computer)
Good luck!
*to find your outside address, go to http://whatismyip.org . When plugging your computer in, go to the command line (Start>Run>CMD for Windows, There are many ways for Linux) and type IPCONFIG (for Windows) or ifconfig (for Linux). Find your IP address in there (if it says something like 192.168.x.x or 10.x.x.x, do an IPCONFIG /RENEW in Windows or ifconfig eth0 down, ifconfig eth0 up in Linux) and compare it with the one you found at http://whatismyip.org
as @MetalMikester said, try putting new firmware on it. I've run into issues with lots of small UDP packets (games) and some of the netgear firmware I've run into. An update almost always fixed it. – skarface – 2010-02-01T05:01:32.667
Can't say I've ever heard of anything like this, but have you checked if an updated firmware is available for the router? – MetalMikester – 2010-01-20T12:59:41.303
I take it you also rebooted your modem and every other parties involved in your internet access? – damusnet – 2010-01-20T13:16:43.433