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Re: Cable Modem CM100 Not Getting Xfinitiy Gigabit Speeds

craycraft
Aspirant

Cable Modem CM100 Not Getting Xfinitiy Gigabit Speeds

Hello,

 

I was just looking for a little bit of guidance on getting the gigabit speeds I pay for from Xfinity.

I'm wondering if the upstream/downstream info the modem is providing seems abdormal? I tried following the guide on signal levels for docsis 3 on pickmymodem.com but still a little lost. Based on the guide it looks like the downstream OFDM channel 2 power is way off would that be correct? Various different speed test methods land me somewhere between 300 - 600 down depending on the time of day. 

Screenshots From Modem 

I'm using a Amplifi HD router and mesh points for the rest of the network. Hardware NAT is enabled and I've seen the router have gigabit throughput a few times. So I'm asusming it's either something with the modem or the ISP. Any help is greatly appeciated!

 

Thanks,

 

Model: CM1000|Ultra-High Speed Cable Modem—DOCSIS® 3.1 Ready
Message 1 of 8
plemans
Guru

Re: Cable Modem CM100 Not Getting Xfinitiy Gigabit Speeds

Your levels look good. Do you have your logs? 

Also for testing do this:

1. connect directly to the modem. Some routers show slowed speeds if any traffic monitoring is on such as parental controls, qos, data usage, etc. 

2. Try different computers. Some older devices can't saturate gigabit speeds. 

3. try several websites. speedtest.net doesn't always choose servers that can saturate gigabit. dslreports.org and googlefiber's speedtest can usually saturate gigabit. 

Message 2 of 8
craycraft
Aspirant

Re: Cable Modem CM100 Not Getting Xfinitiy Gigabit Speeds

I've done all of basic troubleshooting and as I mentioned tried various speed testing methods. It's not anything like that causing the issue. I was a sys admin for years and still work in IT today so the basic stuff I've tried and read plently of post before posting this question. Only stating this so I don't have to wait through ten replies telling me to do the same stuff already mentioned in all of the other similar post on this forum. I've gotten gigabit speeds just a few weeks ago on the exact same setup.

Message 3 of 8
plemans
Guru

Re: Cable Modem CM100 Not Getting Xfinitiy Gigabit Speeds


@craycraft wrote:

I've done all of basic troubleshooting and as I mentioned tried various speed testing methods. It's not anything like that causing the issue. I was a sys admin for years and still work in IT today so the basic stuff I've tried and read plently of post before posting this question. Only stating this so I don't have to wait through ten replies telling me to do the same stuff already mentioned in all of the other similar post on this forum. I've gotten gigabit speeds just a few weeks ago on the exact same setup.


I get that you were a sys admin. 

And saying you've tried everything doesn't tell me what you've tried or what results your getting. 

We can't help with general statements of "I've tried it all, so just tell me the problem". We don't know as we didn't do the testing that you did do. If you want to avoid the 10 replies, then provide more info. Answer the questions I did ask and add any extra test that you've already done such as swapping cables, different pc's, having the isp check the line,  etc.   Help us to help you. 

Message 4 of 8
craycraft
Aspirant

Re: Cable Modem CM100 Not Getting Xfinitiy Gigabit Speeds

Sorry, I didn't mean for that come off as being short with you or anything. I truly appeciate your help and am coming here because I'm unable to figure this out. Just when reading through some post there was a lot of repeating of the same steps by different people and I just wanted to avoid that from starting. Let me provide more info!

 

We moved into a new home about a month and a half ago. I was able to get gigabit speeds for the first few weeks. It's a new construction neighborhood and they're working on the house next to me and a few homes down the street. The home directly infront of us was also recently finished and somneone moved in. I wasn't monitoring the network that closesly but the lack of consistent gigabit speeds seems to have started since the new move ins. Not 100% that is related but figured it's worth mentioning.

I've gotten gigabit with the current setup before. I've also seen gigabit come through randomly in results for an hour here or there but that's it as of the last few weeks. I've gotten it using a Nighthawk X6 and I've seen it using this Amplifi HD setup. Those both handle the wireless and then run a cable to a gigabit switch that then feeds ports around the house. I've seen gigabit speeds from all of these setups and a few of the ethernet ports around the house that I've tested. Only in the last few weeks has it stopped and been unable to provide consistent speeds. The speeds as of yesterday are varying from 200 - 550 down. 

 

For both the Nighthawk and the Amplifi I've tried all kinds of configurations including ones that have gotten gigabit speeds before on this network and am unable to get consisent gigabit now. I've disabled any network monitoring features on both and tested. QOS isn't enabled on either, hopefully I won't need this if I'm able to get consistent throughtput.I've tried enabling and disabling IPV6 on WAN for the Amplifi.  Currently using the Amplifi HD to test with all network monitoring features turned off and HARDWARE NAT turned on. I've seen gigabit results off and on with this exact setup. 

 

Testing methods include:

 

speedtest.net

dslreports.com/speedtest
Nighthawks X6's bult in speed tester

Amplifi HD's bult in performance tested

From the wired machine through the gigabit switch. With all other ports disconnected. Also I've carried that machien up and the down the stairs a countless amount of times now to test the speeds directly wired because none of our laptops have ethernet ports lol. 

 

I've tried factory reseting the CM100 several times now to see if it would pickup a different configuration or something.

 

The results seem to sit between 200 - 600 down the last few days. Different times of day seem to move it from 200 to 500.

Message 5 of 8
craycraft
Aspirant

Re: Cable Modem CM100 Not Getting Xfinitiy Gigabit Speeds

Attaching an updated screengrab of the modem connection.

Message 6 of 8
plemans
Guru

Re: Cable Modem CM100 Not Getting Xfinitiy Gigabit Speeds

If your speeds are less than the 1 gig you pay for at the modem, its not the rest of the network.

that isolates it to 3 things.

1. the modem. potentially could be the modem

2. the line coming in. Your levels look good but its a snapshot. not a continuous monitor. 

3. the hub running to your home. maybe in the construction that was going on, something was messed with. 

 

The only one you yourself can really troubleshoot is your own modem. 

Do you have the logs for it? 

Potentially do you have a backup modem you could test?

 

Otherwise you're limited in relying on your isp to come check your lines and speeds. 

 

Message 7 of 8
craycraft
Aspirant

Re: Cable Modem CM100 Not Getting Xfinitiy Gigabit Speeds

I could run to bestbuy later today and buy another modem to test on and then return it if I don't need to keep it to replace the current one.

I've been running back to back test today and the results are fairly spread out.

 

Speedtest.net 300 to 500

dslreports 300 to 600

googlefiber 600 - 800

Message 8 of 8
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