Troubleshooting Comcast Home Internet Speeds

Random

It turns out the problem was my third-party router, but I had some trouble testing it at first.

The Problem

  • Home internet speed was very slow.
  • Speed tests showed I was getting significantly less than what I was paying for.

My Setup

  • Comcast Xfinity 200mbps
  • cable modem (from Comcast, running in Bridge mode)
  • a third-party router

Troubleshooting

  • Comcast tech support said, “Everything looks good on our end. Is it your router?”
  • Needed to do a speed test without my router, but how?
  • I connected my laptop directly to my cable modem via ethernet adapter dongle. (This can be a big security problem – don’t leave it this way.)
  • My laptop kept saying: “No IP address assigned”

The Solution

  • Found out that when the cable modem is in Bridge mode, it will only assign an IP address to the first device that connects to it. Usually that is my 3P router.
  • I needed to first reboot the cable modem and plug my laptop into it before any other device in order to get an IP address so I could run the speed test.
  • Guess what? It WAS my router! When I connected directly to the cable modem and ran a speed test, I got the speeds I was paying for.