I use theirs(modem). Yes there is a monthly charge. Within the last couple of weeks they had to change mine out. Download speed was fine, upload stopping to a crawl. Makes like not working, but showed had a connection. That is why it is fresh in my mind about the lights on the old and new Arris. Didn't cost me a thing for them to do that, as it is theirs, not mine.
That is maybe why they are telling you only 66 meg. Att maybe only be a docsis 2 modem. If I remember correctly back when I first got the 100 meg service, it was slow. Nowhere near 100. Called about it, they looked up and saw what modem I had(not Arris, different make). Said it was docsis 2, would not be able to get 100 out of it. They set me up with a self install modem and said throw my old 1 out. Hooked up, called to activate new mac address. Instant 100.
Gary, router is something different. Mine here is a Linksys. Outside world to house, modem(charter), router(linksys), computers(2 emachines, 2 custom built gaming).
Nope, don't use the gaming for here. Might work better if I did. I7's with good cards.
Unless you have a combination modem/router. Personally, I believe that is a bad idea. Why you ask? If you have seperate unit and you have a problem, you can always do directly to the modem with 1 computer. If the problem disappears, the router is defective.