U

Visitor

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3 Messages

Tue, May 10, 2022 11:06 PM

Netgear Modem CM1200 + Router AR500 Compatibility?

*I am not educated in this department and need some help and advice* Hi, from doing my own research I want to find some clarification. I just signed up for xfinity 1.2 Gig plan, I’m aware my modem goes up to 2 gig download speed. I’m wanting to hear that I will be able to make use of everything with my setup. I’m hearing that the modem doesn’t make full use of the 1.2 gig? I think from my understanding of reading other posts that I need some certain connection to my router that will efficiently make it work? I apologize if I don’t even know how to explain or properly ask what I need to know.

Accepted Solution

BruceW

Gold Problem Solver

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23.7K Messages

15 d ago

... 1.2 Gig plan ...

Please see https://www.xfinity.com/support/devices. Note that Comcast rates the CM1200 for speeds "Up to 949 Mbps". Using devices on speed tiers for which they are not approved tends to produce unexpected results, often speeds well below the manufacturer's rating. You need to pick one of the modems on the "Devices" page that is approved for the 1.2 Gbps speed tier or drop back to a lower tier.

(edited)

Visitor

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3 Messages

@BruceW​ thank you! Very helpful. 

Accepted Solution

Visitor

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7 Messages

14 d ago

The modem side of the CM1200 may be able to do 2Gbps, but it only has 1Gbps ethernet ports.  The CM1200 supports up to 4 IPs for Comcast business accounts.  I could easily see it managing a total of 2Gbps spread over 2+ ports to multiple computers, etc.  On the consumer side I can't imagine Comcast supporting more than what the single fastest LAN port can manage.  1Gbps gets you ~949 usable.  I usually think of it as "about 950."  There's some protocol overhead that doesn't get reported in a typical speed test.  I wouldn't worry about it from a "working properly" perspective as long as it's around there.  Maybe you can set up LACP or something and use multiple ports but load balancing over multiple links is a pain.  I don't know if a CM1200 would support it.  I write software for a living and could probably figure it out but I don't want to deal with it.  I tried link aggregation once and it's a flaky mess.  If you really want more than about 950Mbps just pay up and upgrade your LAN gear to 2.5Gb or better or get a top end WiFi router and client (aka high end WiFi 6 or 6e WiFi router and client/laptop, and don't go cheap) and stay close to the router.  If 950 is good enough just lower your plan speed a notch so you're not paying for speed you're not using.  "900Mbps" service should max out a 1Gb LAN if all your gear is working well.  Comcast tends to overprovision a bit.  Overprovisoning reduces the number of people with marginal equipment who call up and complain that they're not getting what they paid for.  It's extremely common among consumer ISPs.  If your gear is working well you'll get a little more than your official plan speed.

Official Employee

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187 Messages

15 d ago

Hello @user_616b12, Thank you so much for reaching out to us about your speed and modems concerns. You are in the right place and I am happy to address your concerns. Now You will get a closer speed to the Gigabit plan on a hardwired to the modem with an ethernet cable. On Wi-Fi, the speeds varies on your device you are connecting and how far you are away from the modem. 

Visitor

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3 Messages

13 d ago

Thank you so much for this. I appreciate you taking the time to explain this for me!

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