Question Need help with a new cable modem

gta1216

Commendable
Oct 16, 2019
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I recently upgraded to the Super Fast internet with Xfinity, which offers up to 600 mbps. Since I have an older cable modem (don't remember the model), I continue to get only +/-100 mbps. I was told by Xfinity tech support that only the following 3 modems are capable. Can someone comment whether that is true, or if there are other modems that I can consider? Also, I have 4 Google Wifi (not Nest Wifi) mesh routers. I don't know if that would also create a bottleneck or not.

Recommended modems by Xfinity tech support:

NETGEAR CAX80
NETGEAR NIGHTHAWK CM2000
NETGEAR CM2050V
 
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kanewolf

Titan
Moderator
I recently upgraded to the Super Fast internet with Xfinity, which offers up to 600 mbps. Since I have an older cable modem (don't remember the model), I continue to get only +/-100 mbps. I was told by Xfinity tech support that only the following 3 modems are capable. Can someone comment whether that is true, or if there are other modems that I can consider? Also, I have 4 Google Wifi (not Nest Wifi) mesh routers. I don't know if that would also create a bottleneck or not.

Recommended modems by Xfinity tech support:

NETGEAR CAX80
NETGEAR NIGHTHAWK CM2000
NETGEAR CM2050V
Xfinity has a web page specifically to help you select a modem -- https://www.xfinity.com/support/articles/list-of-approved-cable-modems
 
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There are all kind of strange restrictions on which cable modem work. It can vary a lot even within the same city because of difference in the equipment the ISP is using.

In general you must look at a cable modem as media converter. Its only purpose is to convert the signal on the coax cable to signals on ethernet cable. As long as it meets the requirements for the plan you buy from the ISP it will function fine. In this case some of the modem you list can support 2.5gbit.
If the ISP does not actually require these units for the 600mbps plan then you are paying for extra features you will never be able to use. You really want to buy the lowest cost product that is on the ISP list for the plan you purchase.

Most routers will not bottleneck the connection. If it is really old it might only have 100mbps ethernet ports. In general most devices, even very cheap ones, can run close to gigabit speed WAN/LAN. Now wifi is a completely different story. You likely will get nowhere near 600mbps and it will be much much less if you are
using "mesh" repeater systems. You really want to avoid using any form of wifi repeater if there is any possible way.

My guess is you either have something with a 100mbps port on it or you have a bad ethernet cable. Most cable modem even fairly old ones can run well above 100mbps. BUT there maybe artificial restrictions based on the cable company implementation in the area you live so you are back to first checking the compatibility list on the ISP website. Nobody on the internet can really tell you unless you want to post your address and zip code :)
 
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gggplaya

Distinguished
I have xfinity gigabit, works perfect with my Motorola Docsis 3.1 MB8600 modem. Mine's limited to 1gbps due to the ethernet port only being gigabit.

The MB8611 has a 2.5GBE port.

I've had issues with netgear equipment in the last few years. I don't trust them anymore.
 
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gggplaya

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Did you try Cm1100 or 1200?
No, but my friend had the CM1200. He had to switch to Motorola when he switched to Xfinity Gigabit plan. His modem wouldn't go over 500-600mbps even after a service technician came to his house. He switched to the same Motorola that I had and was instantly at gigabit. It took a few firmware updates, but I think Netgear is still only able to get the CM1200 up to 800mbps on Xfinity. Still won't do the full gigabit: https://community.netgear.com/t5/Cable-Modems-Routers/CM1200-speed-issue-with-Xfinity-Gigabit-service/td-p/1787229

My Motorola has been rock solid, not outages or anything.

I used to love Netgear back in the day, but in the last few years their firmware team has become garbage. Their NAS units are junk, their managed network switch gave me outages, their routers have had issues with software, and their modems gave my friend problems. Some of these items are super simple, like network switches and the cable modem, I'm not sure how they managed to be so bad. I personally won't buy Netgear products anymore, I used to be a fan until their recent product offerings.
 
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