CM1000-1AZNAS xfinity / download speed issues

[mcbullis08]

Hello all,

I am posting here because I am at my wits end with this problem. I have a CM1000 (owned for several years) that has recently started acting up. I pay for the xfinity giga (1200Mbps) service, and up until 2ish months ago I was seeing speeds for 850+ on my main wired PC. Now I can not seem to reliably achieve over 400. I have had a tech out to look into the issue, replaced splitters, cables, fittings, the whole deal to no avail. Second tech hooks his little box up to the modem and bingo, he has 1000 through my modem. Plugs the cable in and is ready 1800 plus. However, I don't see any of this on my end. I have check drivers, firmware, booted into network safemode, and just can't seem to fix the problem. I have also attached power logs. Any help is greatly appreciated.

[Kitsap]

The CM1000 is a modem only.  Netgear says it is good for 800 Mbps on Xfinity.

What router do you have between your CM1000 and your main wired PC?

What version of firmware is installed on your CM1000?

Netgear says it should be V7.01.01 for Xfinity.

Your signal strength (power) levels do not look out of line.

[plemans]

Your power levels look fine. 

You don't tell us what router you have connected to the cm1000 and if you're testing directly connecting a pc/laptop to the modem or running through the router. 

So, have you connected a pc/laptop directly to the modem to test it? 

Or are you running through a router? 

[mcbullis08]

The CM100 is a modem only and according to xfinity should be good up to 927 Mbps. Which I would be happier if I was reliably seeing either of these speeds.

All testing is done wired from modem to PC, while I do have a netgear nighthawk router it is only in use for the house hold use. I disconnect when chasing down issues.

Firmware version on my modem is V7.01.01

[Kitsap]

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@mcbullis08 wrote:

The CM100 is a modem only and according to xfinity should be good up to 927 Mbps. Which I would be happier if I was reliably seeing either of these speeds.

All testing is done wired from modem to PC, while I do have a netgear nighthawk router it is only in use for the house hold use. I disconnect when chasing down issues.

Firmware version on my modem is V7.01.01

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The tech's hardware indicated everything was fine at the modem.  Maybe you should be looking at your main wired PC?  Mac or Windows (version 10 or 11)?

If it is Windows, you get updates every two to four weeks from Microsoft that could adversely impact your network settings.

Network profile, Private or Public?  IPv6 enabled on your router?

[mcbullis08]

Windows 7 ultimate (64 bit) service pack 1&2.

Home network with IPv6 enabled but not being used.

[plemans]

do you have another device you can hardwire into the modem and test with? 

[mcbullis08]

I have also tested with my wife's Macbook OS High Sierra 10.13.6 that has almost identical results.

All of my testing (PC directly connnected, Macbook directly connected, PC modem to router) all produce speeds ranging in the 350-420 range. When 2 months ago was 850-920. Nothing in my setup has changed, which is why I believed it to be a xfinity issue. But when the tech connected to the modem and said he was seeing 900+ down it baffled me.

All the help is greatly appreciated.

[Kitsap]

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@mcbullis08 wrote:

I have also tested with my wife's Macbook OS High Sierra 10.13.6 that has almost identical results.

All of my testing (PC directly connnected, Macbook directly connected, PC modem to router) all produce speeds ranging in the 350-420 range. When 2 months ago was 850-920. Nothing in my setup has changed, which is why I believed it to be a xfinity issue. But when the tech connected to the modem and said he was seeing 900+ down it baffled me.

All the help is greatly appreciated.

Routine troubleshooting questions.  Are you sure your Ethernet cables are good?  Should be Cat 6 or better.  Any corrosion on the Ethernet connection plugs or ports?  Debris or lint in the ports?

[mcbullis08]

I have tried several different cat5e cables but all seem to produce the same results. I find it hard to believe that i have a half dozen that are all bad. Will look into getting a cat6 just to be sure.

First comcast tech replaced the coax under the house, all splitters, and line terminators. Ran a test wire from the box at the street to the back of the house with no change. He, ultimately said there was an issue up on the power pole that had to be addressed. Second tech is the one who produced the appropriate speed results. (No one has worked on the pole yet) I believe that all physical hardware up to the modem to be good.

I am going to reach out to comcast to "rent" a modem to determine if it is indeed my equipment.