Question This is about modems and routers

thailen

Junior Member
Nov 17, 2019
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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.
 

Ichinisan

Lifer
Oct 9, 2002
28,298
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I've had lots of used Arris / Motorola modems. They work fine with my small local cable company. I now have 3 or 4 tested DOCSIS 3.1 modems from thrift stores. Lost a really good one to a lightning strike in February.

My main concern when buying used is that the wired Ethernet port could have been lightning-damaged in a way that prevents it from detecting a physical connection to your router or other device ("no link" on Ethernet / LAN port).
 

WilliamM2

Platinum Member
Jun 14, 2012
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If you already have a good working modem, why not just buy a router? Modem/router combos usually don't have half the options that a seperate router does, or perform as well.
 
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mv2devnull

Golden Member
Apr 13, 2010
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I then needed to find a modem/router to add wi-fi.
Wifi has nothing to do with routers and modems. Granted, combo devices often contain access point too. However, when you need Wifi access point, that is what you should look for.

Let the current working modem continue to perform its task and add separate (whatever provides) Wifi.
 

SamirD

Golden Member
Jun 12, 2019
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To address what you're specifically running across (although the ideas on just getting a router would be my config as well), the combo units are more picky than just the plain modems as there has to be a config file that cox has to push to the unit. If they don't have a config file for it, it won't work. Straight modems are a lot less stringent in this department so they're not as troublesome.

Now, since you've already bought these things, if they have a wan ethernet port, then you can use them just like a straight router and won't have to worry about the modem part letting your current modem handle that part.
 

WaCableTech

Junior Member
Jul 8, 2019
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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.
 

SamirD

Golden Member
Jun 12, 2019
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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.
What have you seen when a modem like this is used with another isp? Are there any issues then?
 
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QuietDad

Senior member
Dec 18, 2005
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What have you seen when a modem like this is used with another isp? Are there any issues then?
I am a contractor and do work or three cable ISPs in the area. Optimum, Comcast and FIOS. Just like previously mentioned I see "customer modems" that are still active on other accounts and just as often, competitors modem wont work on another's system. Sales to stop all o those calls from having the customer supply the MAC ID/serial number and check it before placing the order. Comcast,usually, directs you to come to a customer support center with the modem and your receipt and is usually successful in resolving the problem. IOS and Optimum not as much. Your mileage may vary.
Issues happen on Ebay when people move and take their modem with them and sell them on eBay and never closed their accounts at the last place
 

SamirD

Golden Member
Jun 12, 2019
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I think the issues with competitors modems stopped when manufacturers (like arris) stopped making system specific models. Hence why I was asking if a modem with a current account on one system would work fine on another system if the modem is supposed to be compatible. I wouldn't think it would be an issue between isps because what does one isp care if a customer hasn't paid on their competitor.
 

QuietDad

Senior member
Dec 18, 2005
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Serial numbers and MAC addresses are owned/reserved or specific ISPs. Same way you can't port a cell phone number to a new carrier until the old one says it's OK. Again. The Only way to ix this is to take the modem to a local Customer Service Center with the receipt you should have when you paid or it. I have seen ISP's actually just swap the modem with another one to fix it.
 

SamirD

Golden Member
Jun 12, 2019
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Serial numbers and MAC addresses are owned/reserved or specific ISPs. Same way you can't port a cell phone number to a new carrier until the old one says it's OK. Again. The Only way to ix this is to take the modem to a local Customer Service Center with the receipt you should have when you paid or it. I have seen ISP's actually just swap the modem with another one to fix it.
This doesn't make sense. if I buy a sb6190 from a retailer, how is that bound to an isp? If I use it with one isp and then just move to another, how would they even know about the previous registration?
 

QuietDad

Senior member
Dec 18, 2005
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This doesn't make sense. if I buy a sb6190 from a retailer, how is that bound to an isp? If I use it with one isp and then just move to another, how would they even know about the previous registration?
We have issues all the time with "Retail" modems all the time. Best Buy and Walmart in the area sell cable modems and when they get returned for any reason, they're usually just re-shrink wrapped and put back on the shelf. Many times someone buys one, authorizes it on their ISP account and then returns them or a variety o reasons. The Customer just wants to get rid o it and since it's a customer modem, the ISP doesn't care. Customers usually don't call the ISP to "cancel" a modem".
All I can say is I see i3-5 times a week. Again. The only options you have is the Customer Service Center or you ISP with reciept in hand or going back to vhe vendor you purchased toe router rom and swap it or another one as, since it can't be used, I can't see a retailer not taking it back as "defective"
 

SamirD

Golden Member
Jun 12, 2019
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We have issues all the time with "Retail" modems all the time. Best Buy and Walmart in the area sell cable modems and when they get returned for any reason, they're usually just re-shrink wrapped and put back on the shelf. Many times someone buys one, authorizes it on their ISP account and then returns them or a variety o reasons. The Customer just wants to get rid o it and since it's a customer modem, the ISP doesn't care. Customers usually don't call the ISP to "cancel" a modem".
All I can say is I see i3-5 times a week. Again. The only options you have is the Customer Service Center or you ISP with reciept in hand or going back to vhe vendor you purchased toe router rom and swap it or another one as, since it can't be used, I can't see a retailer not taking it back as "defective"
I get that when it happens with the same isp, what I'm asking is about different isps.

Someone buys a modem from walmart activates it with comcast and then returns it. Next buyer buys the modem and wants to activate it on wow--how would wow even know it was registered with comcast? Or even care?