All lights are flashing in unison. comcast says I need a new modem. Is this true?

For mine, I just pulled out the battery for a few moments and the lights went normal, then put the battery back in. It's still normal. Figured that the battery light was the only one not flashing in unison with the others.

Good luck. :)

From my limited experience with this problem, the answer can be yes. If you cannot unplug the modem power plug and reattach it, and then make it "set up" and work, the problem is either a bad line feed or bad modem. The easiest thing to do is try another modem...that will verify if the line is good. If the line is bad, comcast has to fix it for free, to provide your service. It your modem is good, you won't have to replace it and buy another one(however, they may charge a service fee, I'm not sure if or how much- call them and check first). Hope this helps.