I signed up with Cox Internet 2 months ago and installed an ARRIS modem compatible with Cox. So far, so good. I then needed to find a modem/router to add wi-fi. So I bought a used ARRIS modem/router compatible with Cox and had a Cox technician attempt to install it. It didn't work. So I assumed it was a bad modem. I then purchased another Cox-compatible modem/router(a used ARRIS product) and had a Cox technician attempt to install THAT one, Same result. So I'm wondering, first, whether it's common for used modems to not work? Or just to pay 4x the cost and buy a new one? Or is there another reason and another solution? BTW, my initial ARRIS modem was used and it works fine.
If the initial device is just a modem you can buy JUST a router to add to it, combo units generally do not have great wifi range, just a FYI.
Arris used to be a emta [phone modem company, and not a small one they made major cable system parts] then a little patent infringement lawsuit between Google and Motorola reared its head and when it looked like moto had a leg to stand on, google bought them, dropped the suit, and sold off the Motorola cable division parts mainly to arris making them an even larger cable modem company. There are some things that need to be considered, when you buy these used modems, they need to NOT be on a cox account, you cannot have a modem on 2 accounts so the system will frown on that. A lot of customers do NOT remove modems from their account when selling them. I work for Comcast, and see this weekly. There is nothing I can do if its on another comcast account they cannot use them until THAT person calls in and has it removed from their old account.
For any used router [combo or standalone] I recommend holding down the reset button with a paper clip and counting to 30 like you are FOREST GUMP. This will do a full reset and set the device as if you just unwrapped it from the packaging when it was new.