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Wild Variances in Gigabit Speed Test Results

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Wild Variances in Gigabit Speed Test Results

I upgraded our home to Gigabit internet recently and have been performing tests regularly with wildly varied results. I performed a few test downloads and noticed no appreciable difference in speed from my previous 250mb tier. All tests were performed on a Windows 10 box with a gigabit NIC directly wired to the modem. The results always showed fastest on Xfinity's servers typically around 940mb, but from OOKLA, I never got hire than 300mb. DSLReports also showed 940mb, with others around 250-200mb mark. Not sure who to believe, but it seems that most with gigabit service from Xfinity were getting much smaller variances between speed tests and different sites. I have posted a few screenshots with tests results, as well the diagnostics of my Netgear CM1000 modem. A visit is scheduled for tomorrow, but I will probably have to cancel and will be unavailable for a visit for a few weeks (Work, vacation, life, etc.). I have spoken to CS a couple times and they assure that my account is correctly provisioned. I have also spoken to advanced technical support and they state that my signal shows within tolerances. As you an imagine, this is somewhat frustrating so any help would be appreciated.

 

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Startup Procedure                  
Procedure Status Comment
Acquire Downstream Channel 651000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Configuration File OK d11_m_cm1000_gigabit_c01.cm
Security Enable BPI+
IP Provisioning Mode Honor MDD IPv6 only
                   

                   
Downstream Bonded Channels                    
Channel Lock Status Modulation Channel ID Frequency Power SNR / MER Unerrored Codewords Correctable Codewords Uncorrectable Codewords
1 Locked QAM256 32 651000000 Hz -1.1 dBmV 38.6 dB 175181707 11 57
2 Locked QAM256 1 465000000 Hz -1.2 dBmV 41.2 dB 157119815 15 56
3 Locked QAM256 2 471000000 Hz -1.1 dBmV 41.2 dB 157123448 16 54
4 Locked QAM256 3 477000000 Hz -0.9 dBmV 41.1 dB 157126943 13 59
5 Locked QAM256 4 483000000 Hz -0.8 dBmV 41.0 dB 157130677 10 59
6 Locked QAM256 5 489000000 Hz -0.6 dBmV 41.0 dB 157134211 8 67
7 Locked QAM256 6 495000000 Hz -0.4 dBmV 39.9 dB 157138188 13 61
8 Locked QAM256 7 501000000 Hz -0.4 dBmV 40.8 dB 157141945 11 60
9 Locked QAM256 8 507000000 Hz -0.8 dBmV 40.9 dB 157145719 15 56
10 Locked QAM256 10 519000000 Hz -0.9 dBmV 40.4 dB 157149199 20 51
11 Locked QAM256 11 525000000 Hz -0.9 dBmV 40.5 dB 157153226 11 62
12 Locked QAM256 12 531000000 Hz -1.0 dBmV 40.3 dB 157156420 3 67
13 Locked QAM256 13 537000000 Hz -1.2 dBmV 40.2 dB 157160517 11 58
14 Locked QAM256 14 543000000 Hz -1.4 dBmV 38.3 dB 157164299 20 52
15 Locked QAM256 15 549000000 Hz -1.6 dBmV 39.1 dB 157168027 15 59
16 Locked QAM256 16 555000000 Hz -2.1 dBmV 40.2 dB 157172227 12 59
17 Locked QAM256 17 561000000 Hz -2.8 dBmV 39.9 dB 157177517 8 62
18 Locked QAM256 18 567000000 Hz -3.7 dBmV 39.6 dB 157181365 10 60
19 Locked QAM256 19 573000000 Hz -3.2 dBmV 39.8 dB 157185098 9 60
20 Locked QAM256 20 579000000 Hz -2.0 dBmV 40.3 dB 157188568 12 58
21 Locked QAM256 21 585000000 Hz -1.6 dBmV 28.8 dB 157178845 13850 59
22 Locked QAM256 22 591000000 Hz -1.7 dBmV 31.8 dB 157196452 13 56
23 Locked QAM256 23 597000000 Hz -1.8 dBmV 40.1 dB 157199606 10 60
24 Locked QAM256 24 603000000 Hz -1.8 dBmV 40.0 dB 157204161 10 59
25 Locked QAM256 25 609000000 Hz -1.3 dBmV 40.1 dB 157207844 13 59
26 Locked QAM256 26 615000000 Hz -1.0 dBmV 40.1 dB 157211615 10 62
27 Locked QAM256 27 621000000 Hz -0.8 dBmV 40.2 dB 157215083 17 53
28 Locked QAM256 28 627000000 Hz -0.9 dBmV 39.5 dB 157219054 11 60
29 Locked QAM256 29 633000000 Hz -0.9 dBmV 39.9 dB 157222682 11 60
30 Locked QAM256 30 639000000 Hz -0.6 dBmV 40.2 dB 157223759 17 54
31 Locked QAM256 31 645000000 Hz -0.7 dBmV 40.0 dB 157223401 11 59
32 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0 0
                   

                   
Upstream Bonded Channels (Partial Service)                    
Channel Lock Status Modulation Channel ID Frequency Power
1 Locked ATDMA 41 17300000 Hz 51.0 dBmV
2 Locked ATDMA 42 23700000 Hz 51.8 dBmV
3 Locked ATDMA 43 30100000 Hz 50.3 dBmV
4 Locked ATDMA 44 36500000 Hz 51.5 dBmV
5 Not Locked Unknown 0 0 Hz 0.0 dBmV
6 Not Locked Unknown 0 0 Hz 0.0 dBmV
7 Not Locked Unknown 0 0 Hz 0.0 dBmV
8 Not Locked Unknown 0 0 Hz 0.0 dBmV
                   

                   
Downstream OFDM Channels                    
Channel Lock Status Modulation / Profile ID Channel ID Frequency Power SNR / MER Active Subcarrier Number Range Unerrored Codewords Correctable Codewords Uncorrectable Codewords
1 Locked 0, 255 33 672000000 Hz -0.6 dBmV 29.3 dB 1108 ~ 2987 318350081 311700482 1964
2 Not Locked 0, 255 0 0 Hz -5.7 dBmV 0.0 dB 0 ~ 4095 0 0 0
                   

                   
Upstream OFDMA Channels
Channel Lock Status Modulation / Profile ID Channel ID Frequency Power          
1 Not Locked Unknown 0 0 Hz 0 dBmV          
2 Not Locked Unknown 0 0 Hz 0 dBmV          
Official Employee

Re: Wild Variance in Speed Test Results on Gigabit Internet

Hi there, ProAm500. Welcome and thanks for reaching out here for support. We can definitely look into this. It does look like there are some signal issues present, causing your modem a bit of difficulty. Our speed test site: http://speedtest.xfinity.com/ and DSL reports are reliable sources that I would stick to for running speed tests. As far as the download issue you mentioned, that does rely heavily on the source that you are downloading from - in addition to your level of service. Did you end up going forward with that technician visit? 


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Official Employee

Re: Wild Variances in Gigabit Speed Test Results

Hi, ProAm500. I ended up not hearing back from you on this, so I have completed the interaction. If you end up needing further support from me on this, feel free to send me a private message.

 

To send a private message, please click my name "ComcastMorgan" then select "Send a Message" on the right side.

 


I am an Official Comcast Employee.
Official Employees are from multiple teams within Comcast: CARE, Product, Leadership. We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!