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Only getting 20-30% of 1G bandwidth

Frequent Visitor

Only getting 20-30% of 1G bandwidth

I upgraded to 1G. Installed the SB8200 modem. I installed an 8db attenuator as I read that this is likely needed for this modem. With and without the attenuator installed, all speedtest, even directly connected to the SB8200 is only giving me 200-320Mb down. The Arris specs on the modem dB levels look great. So I am not sure why I am getting such terrible speeds on a 1G connection.

 

Channel ID Lock Status Modulation Frequency Power SNR/MER Corrected Uncorrectables
31 Locked QAM256 453000000 Hz -6.5 dBmV 39.6 dB 0 0
1 Locked QAM256 477000000 Hz -5.9 dBmV 39.8 dB 0 0
2 Locked QAM256 483000000 Hz -5.9 dBmV 39.7 dB 0 0
3 Locked QAM256 489000000 Hz -6.2 dBmV 38.9 dB 0 0
4 Locked QAM256 495000000 Hz -6.0 dBmV 39.6 dB 0 0
5 Locked QAM256 507000000 Hz -6.5 dBmV 39.6 dB 0 0
6 Locked QAM256 513000000 Hz -6.8 dBmV 39.6 dB 0 0
7 Locked QAM256 519000000 Hz -7.2 dBmV 39.1 dB 0 0
8 Locked QAM256 525000000 Hz -7.0 dBmV 39.4 dB 0 0
9 Locked QAM256 531000000 Hz -6.8 dBmV 39.4 dB 0 0
10 Locked QAM256 537000000 Hz -6.7 dBmV 39.5 dB 0 0
11 Locked QAM256 543000000 Hz -6.4 dBmV 39.7 dB 0 0
12 Locked QAM256 549000000 Hz -6.5 dBmV 39.6 dB 0 0
13 Locked QAM256 555000000 Hz -6.6 dBmV 39.5 dB 0 0
14 Locked QAM256 561000000 Hz -6.7 dBmV 39.5 dB 0 0
15 Locked QAM256 567000000 Hz -6.9 dBmV 39.5 dB 0 0
16 Locked QAM256 573000000 Hz -6.9 dBmV 39.5 dB 0 0
17 Locked QAM256 579000000 Hz -7.2 dBmV 39.4 dB 0 0
18 Locked QAM256 585000000 Hz -7.2 dBmV 39.4 dB 0 0
19 Locked QAM256 591000000 Hz -7.5 dBmV 39.3 dB 0 0
20 Locked QAM256 597000000 Hz -7.4 dBmV 39.3 dB 0 0
21 Locked QAM256 603000000 Hz -7.3 dBmV 39.5 dB 0 0
22 Locked QAM256 609000000 Hz -7.4 dBmV 39.5 dB 0 0
23 Locked QAM256 615000000 Hz -7.0 dBmV 39.6 dB 0 0
24 Locked QAM256 621000000 Hz -6.9 dBmV 39.7 dB 0 0
25 Locked QAM256 627000000 Hz -6.8 dBmV 39.5 dB 0 0
26 Locked QAM256 633000000 Hz -6.9 dBmV 39.6 dB 0 0
27 Locked QAM256 639000000 Hz -7.0 dBmV 39.6 dB 0 0
32 Locked Other 722000000 Hz -6.2 dBmV 36.8 dB 7976328 0
33 Not Locked QAM256 0 Hz 0.0 dBmV 39.6 dB 0 0
34 Locked QAM256 459000000 Hz -6.5 dBmV 39.7 dB 0 0
35 Locked QAM256 465000000 Hz -6.2 dBmV 39.8 dB 0 0


 

 
Upstream Bonded Channels
Channel Channel ID Lock Status US Channel Type Frequency Width Power
1 1 Locked SC-QAM Upstream 35800000 Hz 6400000 Hz 58.0 dBmV
2 2 Locked SC-QAM Upstream 29400000 Hz 6400000 Hz 50.0 dBmV
3 3 Locked SC-QAM Upstream 23000000 Hz 6400000 Hz 51.0 dBmV
4 4 Locked SC-QAM Upstream 16600000 Hz 6400000 Hz 50.0 dBmV
Expert

Re: Only getting 20-30% of 1G bandwidth

Take it out. It's killing both the up and the down power levels !



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Frequent Visitor

Re: Only getting 20-30% of 1G bandwidth

OK so did that. But still getting only 27% (270Mb/avg) via Xfinity speed test. Any idea what else I should try?

 

Procedure Status Comment
Acquire Downstream Channel 453000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Configuration File OK  
Security Enabled BPI+
DOCSIS Network Access Enabled Allowed  

 

 
Downstream Bonded Channels
Channel ID Lock Status Modulation Frequency Power SNR/MER Corrected Uncorrectables
31 Locked QAM256 453000000 Hz 1.4 dBmV 39.9 dB 0 0
1 Locked QAM256 477000000 Hz 1.9 dBmV 40.1 dB 0 0
2 Locked QAM256 483000000 Hz 1.9 dBmV 40.0 dB 0 0
3 Locked QAM256 489000000 Hz 1.6 dBmV 39.2 dB 0 0
4 Locked QAM256 495000000 Hz 1.8 dBmV 39.9 dB 0 0
5 Locked QAM256 507000000 Hz 1.4 dBmV 40.0 dB 0 0
6 Locked QAM256 513000000 Hz 1.0 dBmV 39.8 dB 0 0
7 Locked QAM256 519000000 Hz 0.6 dBmV 39.5 dB 0 0
8 Locked QAM256 525000000 Hz 0.8 dBmV 39.7 dB 0 0
9 Locked QAM256 531000000 Hz 1.0 dBmV 39.5 dB 0 0
10 Locked QAM256 537000000 Hz 1.3 dBmV 40.0 dB 0 0
11 Locked QAM256 543000000 Hz 1.4 dBmV 40.1 dB 0 0
12 Locked QAM256 549000000 Hz 1.3 dBmV 40.0 dB 0 0
13 Locked QAM256 555000000 Hz 1.3 dBmV 40.1 dB 0 0
14 Locked QAM256 561000000 Hz 1.2 dBmV 40.0 dB 0 0
15 Locked QAM256 567000000 Hz 1.0 dBmV 39.9 dB 0 0
16 Locked QAM256 573000000 Hz 1.0 dBmV 40.0 dB 0 0
17 Locked QAM256 579000000 Hz 0.6 dBmV 39.8 dB 0 0
18 Locked QAM256 585000000 Hz 0.6 dBmV 39.9 dB 0 0
19 Locked QAM256 591000000 Hz 0.5 dBmV 39.9 dB 0 0
20 Locked QAM256 597000000 Hz 0.5 dBmV 39.8 dB 0 0
21 Locked QAM256 603000000 Hz 0.8 dBmV 40.0 dB 0 0
22 Locked QAM256 609000000 Hz 0.7 dBmV 40.0 dB 0 0
23 Locked QAM256 615000000 Hz 1.1 dBmV 40.2 dB 0 0
24 Locked QAM256 621000000 Hz 1.0 dBmV 39.5 dB 0 0
25 Locked QAM256 627000000 Hz 1.2 dBmV 40.1 dB 0 0
26 Locked QAM256 633000000 Hz 1.0 dBmV 40.1 dB 0 0
27 Locked QAM256 639000000 Hz 1.2 dBmV 40.1 dB 0 0
32 Locked Other 722000000 Hz 2.0 dBmV 35.2 dB 12630009 0
33 Not Locked QAM256 0 Hz 0.0 dBmV 40.0 dB 0 0
34 Locked QAM256 459000000 Hz 1.3 dBmV 40.1 dB 0 0
35 Locked QAM256 465000000 Hz 1.6 dBmV 40.2 dB 0 0


 

 
Upstream Bonded Channels
Channel Channel ID Lock Status US Channel Type Frequency Width Power
1 1 Locked SC-QAM Upstream 35800000 Hz 6400000 Hz 50.0 dBmV
2 2 Locked SC-QAM Upstream 29400000 Hz 6400000 Hz 42.0 dBmV
3 3 Locked SC-QAM Upstream 23000000 Hz 6400000 Hz 43.0 dBmV
4 4 Locked SC-QAM Upstream 16600000 Hz 6400000 Hz 42.0 dBmV
Expert

Re: Only getting 20-30% of 1G bandwidth

Sorry for any confusion ! I didn't mean to imply that that was the surefire fix for your issue, only that it needed to be addressed no matter what else is going on.

 

Anything apply here ? ;

 

https://forums.xfinity.com/t5/Your-Home-Network/Troubleshooting-Gigabit-internet-speeds/m-p/3145413#...



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Frequent Visitor

Re: Only getting 20-30% of 1G bandwidth

Yep, I've tried all of those (network engineer by trade). I factory resetting everything too. Forced full 1G/Full duplex and no difference. It's very sporadic. I am however seeing these messages:

 

11/08/2019 15:31 82000200 3 "No Ranging Response received - T3 time-out;CM-MAC=XX:XX:XX:XX:XX;CMTS-MAC=00:01:5c:92:90:5f;CM-QOS=1.1;CM-VER=3.1;"
11/08/2019 15:30 82000800 3 "16 consecutive T3 timeouts while trying to range on upstream channel 1;CM-MAC=XX:XX:XX:XX:XX;CMTS-MAC=00:01:5c:92:90:5f;CM-QOS=1.1;CM-VER=3.1;"
11/08/2019 15:30 82000300 3 "Ranging Request Retries exhausted;CM-MAC=XX:XX:XX:XX:XX;CMTS-MAC=00:01:5c:92:90:5f;CM-QOS=1.1;CM-VER=3.1;"
Expert

Re: Only getting 20-30% of 1G bandwidth

What do you get for the upload speed ?



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Frequent Visitor

Re: Only getting 20-30% of 1G bandwidth

i'm getting 21Mbps on the up

Expert

Re: Only getting 20-30% of 1G bandwidth

O/k the modem may not be provisioned correctly for the gigabit speed tier.

 

Try calling 1-800-comcast and ask a rep to completely remove the modem from your account and to "re-provision" it from scratch. Also ask them to confirm that the provisioning and account data in their database is correct and complete and that the correct configuration / bootfile for your subscribed to speed tier is being pushed to the modem.



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Frequent Visitor

Re: Only getting 20-30% of 1G bandwidth

We just tried a complete re-provision for 1G and still no difference. A tech is scheduled to come onsite in a couple days. Hopefully they can fix it.

Expert

Re: Only getting 20-30% of 1G bandwidth

O/k. Please post back again with how the tech visit turns out.



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Frequent Visitor

Re: Only getting 20-30% of 1G bandwidth

Still not resolved.  Still only getting 30% down using xfinity speed test. No better on others. Tech says there were issues with the lines outside. A filter on the line was causing an issue. Says we now have 4 working frequencies or lines? coming to the house. Come to test directly off the modem and it's still garbage. The techs excuse is that it's my modem. Umm hello, show me an RFC test off your side first before  blaming my brand new hardware. He said he would have to provision a new modem and have me rent it in order for me to test that. I knew this was a lazy answer. Apparently there is only one guy in the area with an RFC tester. I basically let the guy go because when a tech tells you to give it a few days, that's a sign they don't know much or they're being lazy. I told him I should at the very minimum get no worse then 700 down but I'm not even getting that. So at this point, I don't know what to do.

 

Procedure Status Comment
Acquire Downstream Channel 483000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Configuration File OK  
Security Enabled BPI+
DOCSIS Network Access Enabled Allowed  

 

 
Downstream Bonded Channels
Channel ID Lock Status Modulation Frequency Power SNR/MER Corrected Uncorrectables
2 Locked QAM256 483000000 Hz 4.8 dBmV 39.9 dB 0 0
3 Locked QAM256 489000000 Hz 4.3 dBmV 39.0 dB 0 0
4 Locked QAM256 495000000 Hz 4.6 dBmV 39.8 dB 0 0
5 Locked QAM256 507000000 Hz 4.5 dBmV 39.8 dB 0 0
6 Locked QAM256 513000000 Hz 4.5 dBmV 39.9 dB 0 0
7 Locked QAM256 519000000 Hz 4.2 dBmV 39.4 dB 0 0
8 Locked QAM256 525000000 Hz 4.2 dBmV 39.8 dB 0 0
9 Locked QAM256 531000000 Hz 4.1 dBmV 39.7 dB 0 0
10 Locked QAM256 537000000 Hz 4.4 dBmV 39.9 dB 0 0
11 Locked QAM256 543000000 Hz 4.4 dBmV 40.1 dB 0 0
12 Locked QAM256 549000000 Hz 4.3 dBmV 40.0 dB 0 0
13 Locked QAM256 555000000 Hz 4.1 dBmV 39.9 dB 0 0
14 Locked QAM256 561000000 Hz 4.1 dBmV 39.9 dB 0 0
15 Locked QAM256 567000000 Hz 4.1 dBmV 39.8 dB 0 0
16 Locked QAM256 573000000 Hz 4.1 dBmV 40.0 dB 0 0
17 Locked QAM256 579000000 Hz 4.0 dBmV 39.9 dB 0 0
18 Locked QAM256 585000000 Hz 4.0 dBmV 39.3 dB 0 0
19 Locked QAM256 591000000 Hz 3.9 dBmV 39.7 dB 0 0
20 Locked QAM256 597000000 Hz 3.8 dBmV 39.2 dB 0 0
21 Locked QAM256 603000000 Hz 4.2 dBmV 39.8 dB 0 0
22 Locked QAM256 609000000 Hz 4.0 dBmV 39.9 dB 0 0
23 Locked QAM256 615000000 Hz 4.5 dBmV 40.2 dB 0 0
24 Locked QAM256 621000000 Hz 4.4 dBmV 40.1 dB 0 0
25 Locked QAM256 627000000 Hz 4.4 dBmV 40.1 dB 0 0
26 Locked QAM256 633000000 Hz 4.5 dBmV 40.1 dB 0 0
27 Locked QAM256 639000000 Hz 4.5 dBmV 40.1 dB 0 0
28 Locked QAM256 645000000 Hz 4.5 dBmV 40.0 dB 0 0
29 Locked QAM256 651000000 Hz 4.4 dBmV 40.2 dB 0 0
30 Locked QAM256 657000000 Hz 4.4 dBmV 40.0 dB 0 0
32 Locked Other 722000000 Hz 5.3 dBmV 32.5 dB 27707264 0
36 Not Locked QAM256 0 Hz 0.0 dBmV 40.0 dB 0 0
37 Locked QAM256 663000000 Hz 4.0 dBmV 39.9 dB 0 0


 

 
Upstream Bonded Channels
Channel Channel ID Lock Status US Channel Type Frequency Width Power
1 2 Locked SC-QAM Upstream 29400000 Hz 6400000 Hz 43.0 dBmV
2 1 Locked SC-QAM Upstream 35800000 Hz 6400000 Hz 43.0 dBmV
3 3 Locked SC-QAM Upstream 23000000 Hz 6400000 Hz 43.0 dBmV
4 4 Locked SC-QAM Upstream 16600000 Hz 6400000 Hz 43.0 dBmV
Expert

Re: Only getting 20-30% of 1G bandwidth

I'm going to escalate your issue to the Comcast corporate employees that are available to these boards. They will be able to poll the CMTS to see whether or not everything is in the green zone, see your node / cable plant and modem health, and also see a history plot for the modem. You should get a reply here in your topic. Good luck !



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Official Employee

Re: Only getting 20-30% of 1G bandwidth

Hi,  thefilmguy. Appreciate you posting and working publicly up to this point. Since the issue continues, we can take a look at things on this end to see what else we can do for you. Once we do that, we can discuss what other options we have at this point for resolution and getting everything figured out for you. It would also be good if you could post a couple speed tests you've completed (https://speedtest.xfinity.com/) here in this thread. We recommend them being spaced out a bit from each other for accuracy reasons.

 

Please send us a private message with your name and we will go from there.

 

To send a private message, please click our name "Comcast_Support" then select "Send a Message" on the right side. Thanks!


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