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Not getting Gigabit Internet speeds

New Poster

Not getting Gigabit Internet speeds

I recently started a service for Gigabit Internet, but I'm not receiving speeds that reflect the advertised speeds. Speedtest results are showing 30/5 Mbps. I had a Comcast technician come and he verified that all the connections and wiring were good, but he was unable to continue because it was a personal modem. I have a Netgear CM700 cable modem which shows up on the list of compatible devices. What can I do here?

Gold Problem Solver

Re: Not getting Gigabit Internet speeds


wongderful wrote: ... Gigabit Internet ... Netgear CM700 ...

Although Netgear rates the CM700 for speeds "up to 1.4 Gbps", Comcast only rates it for speeds up to 701 Mbps. See https://mydeviceinfo.xfinity.com/device/netgear-cm700-557. You might think Comcast would operate the device at 701 Mbps on Gigabit service, but they typically do not create config files for device and speed combinations they don't support.

 

Try using https://mydeviceinfo.xfinity.com/ to find a compatible device. Select the "Download Speed 1000 Mbps" radio button.

Expert

Re: Not getting Gigabit Internet speeds

Just wanted to add to what BruceW said, to use the gigabit service, you need a DOCSIS 3.1 modem even though Comcast has been iffy on letting you use your own for gigabit service.
Silver Problem Solver

Re: Not getting Gigabit Internet speeds


wongderful wrote:

I recently started a service for Gigabit Internet, but I'm not receiving speeds that reflect the advertised speeds. Speedtest results are showing 30/5 Mbps. I had a Comcast technician come and he verified that all the connections and wiring were good, but he was unable to continue because it was a personal modem. I have a Netgear CM700 cable modem which shows up on the list of compatible devices. What can I do here?


Do you have the hardware to support gigabit?

 

Please be aware that due to Ethernet overhead on a 1G link, actual speeds might be limited to 940 Megabytes per second. CPU: Intel Dual Core i5 2.5GHz or better or AMD Dual Core K10 2.5GHz or better. OS Requirements: Windows 8.1 (64 bit) or newer or Mac OSX 10.8 or newer. Memory: 8 GB.

I am not a Comcast employee; I am just a customer, volunteering my time to help other customers here in the Forums.
Gold Problem Solver

Re: Not getting Gigabit Internet speeds


RobertWy wrote: ... Ethernet overhead ... CPU ... OS ... Memory ...

None of these factors are likely to cause 1000 Mbps service to run at 30 Mbps, but using a modem, eMTA, or gateway device not approved for the speed tier very likely will.

Diamond Problem Solver

Re: Not getting Gigabit Internet speeds

OP was using a CM700 modem. Comcast likely does not have a 1000 Mbps configuration / bootfile written for the non-supported modem so a default "Performance" 25/5 speedtier config file gets pushed to it.

New Poster

Re: Not getting Gigabit Internet speeds

EG is likely right. My (less capable) D-Link DCM-301 did the same thing when I upgraded plans.

 

As of this writing there are only 3 DOCSIS 3.1 modems available. a Netgear, an Arris, and the Motorola MB8600. I ended up choosing the Motorola MB8600. It has the better Amazon reviews, and it is the most future-proofed offering. It has 4 ports, and allows port-bonding for more speed (though you would have to have a plan that supported that extra speed). Another bonus is it is the MB8600 is the least expensive of the three.

 

Operating system is not really a problem. I am using Lubuntu 16.04 without any type of issue. (It's just that they are more familiar with - and have more tools for - Windows and MacOS.

New Poster

Re: Not getting Gigabit Internet speeds

For anyone not getting Gigabit Speeds, but have the required DOCSIS 3.1 modem,

 

If you are able to get the speeds plugged directly into the modem, but not through your router, make sure you have Cut-Through Forwarding (CTF) enabled in your router. I had custom firmware (Tomato) on my Tenda AC15, and was only getting ~250Mbps speeds. I found some helpful posts mentioning enabling CTF, and found an option in my Tomato firmware. After enabling it, BAM!! I began to have near/Gigabit speeds.