My kid (14 y.o.) knew the security key password and now it works!
As for why shouldn't I just junk the comcast router, I suppose I'll ask the naive question. What happens when I have router problems and I need to call someone?
Excellent. Glad to hear that worked out. I presume you wrote it down somewhere.
Now to your question.
As preamble, I am a longtime Comcast user, and for the first 10 or so years I purchased my own WiFi router that I attached to their modem, and then I got lazy (also, I moved) and for the past year and a half I've been using the modem and router they gave me when they set up my new service. BTW, I have Xfinity Triple Play, so all of my services (phone, internet, TV) go through Comcast.
In that year and a half, I have never had a problem with the WiFi router that powering the thing off and back on didn't resolve. Prior to that, I had numerous occasions where, for example, internet service went out but I still had TV. In that situation, I was able to check that the problem was Comcast's and not mine by simply pulling the ethernet cable (that goes from the modem to the router) out of the router and plugging it into my laptop. I honestly can't recall a single time that something went wrong with the WiFi router itself that wasn't just an ordinary freeze-up, i.e., the old power cycle trick resolved it.
If I weren't so lazy, I would readily go out and replace all their equipment now with purchased equipment. But, unfortunately, I am. However, other people are less lazy than I.
So, here are my caveats if I were advising such a person. The biggest hurdle will be actually setting up the modem and router the first time. In general, I've found this pretty easy and the instructions very straightforward. On the other hand I am 100% certain that my wife, an otherwise highly educated and high functioning individual, would completely freak out were she to try and do this. (You'll probably know if you're similarly inclined, and if so, I would advise you to stick with all Comcast equipment.) I am also 100% certain that my college-age son, who is not of an engineering bent and whose computer knowledge is limited to the Windows Office products, could also hook up said equipment, no problem. And that's because he's not a technophobe, even if he isn't very knowledgeable. Hopefully that gives you some idea of the difficulty of doing this. If your 14-yr old kid is at all comfortable with computers, he'll probably be able to do it.
Second, make sure you get a DOCSIS 3.0 compliant modem/router--this is the standard required by every ISP these days. They'll have a list of compatible modems, so just make sure the one you want to get is on their list before you get it. Also, make sure it's not the very cheapest model because you'll sacrifice speed and upgradeability as network speeds improve. For example, make sure it has gigabit ports on it. This shouldn't cost too much.
Finally, get an ethernet cable that you can plug into your modem/router and hook to your computer when needed, because as I explained above there are times when you need to check if the problem is your equipment or Comcast, and this is one of the best ways to do that. As for the power cycle thing, you can just pull the plug out of the wall, wait for all the lights to die, and then plug it back in.
That's it