Comcast phone support is basically useless, since the only thing they can do is reset your modem or send a technician out. With intermittent problems, a technician probably isn't going to be able to help much. Here's what Motorola will tell you if you call them, so you'll at least be able to see the same signal information that a technician will:
- Restart the modem, then plug your computer directly into it and get an IP address.
- Go to http://192.168.100.1 and click on the Signal page
- Look at the signal-to-noise ratio. This should be above 25 dB or else you won't be able to get a good signal.
- Look at the downstream power levels. Ideally this is between -15 and 15 dBmV, but values closer to 0 are best.