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Like most I’m on Xfinity with my own S33 modem. I updated my service to an 800Mbps/100Mbps plan and haven’t been able to get anywhere higher than 11.8Mbps uploads on the Xfinity speedtest site. A tech came out and ran a new line today and we removed a splitter that was no longer needed and he said the signal levels were much improved. The only thing I’ve seen improve so far is the number of correctable and uncorrectable errors on channel 1 have gone away with the new line. Otherwise, the power levels on the upstream connection actually seem to have dropped (maybe that’s ok) from 47.5 dBmV to 43.0 dBmV. I’m still not getting any higher than the 11.8Mbps even though I’d expect to at least hit 20Mbps if they still haven’t opened up support to 100Mbps to the S33.

Here are the levels from the modem status page after the new line was installed (and splitter removed). Does anything stand out as a problem? Xfinity support replied that they’re showing downstream SNR is at 44.5 and your upstream SNR is 40.6 and everything within spec on their end.

 

Channel ID Lock Status Modulation Frequency Power SNR/MER Corrected Uncorrectables
4 Locked QAM256 453000000 Hz -1 dBmV 44 dB 0 0
1 Locked QAM256 435000000 Hz -1 dBmV 44 dB 0 0
2 Locked QAM256 441000000 Hz -1 dBmV 44 dB 0 0
3 Locked QAM256 447000000 Hz -1 dBmV 44 dB 0 0
5 Locked QAM256 459000000 Hz -1 dBmV 44 dB 0 0
6 Locked QAM256 465000000 Hz -1 dBmV 44 dB 0 0
7 Locked QAM256 471000000 Hz -1 dBmV 44 dB 0 0
8 Locked QAM256 477000000 Hz -1 dBmV 44 dB 0 0
9 Locked QAM256 483000000 Hz -1 dBmV 44 dB 0 0
10 Locked QAM256 489000000 Hz 0 dBmV 44 dB 0 0
11 Locked QAM256 495000000 Hz -1 dBmV 44 dB 0 0
12 Locked QAM256 501000000 Hz -1 dBmV 44 dB 0 0
13 Locked QAM256 507000000 Hz -1 dBmV 44 dB 0 0
14 Locked QAM256 513000000 Hz -1 dBmV 44 dB 0 0
15 Locked QAM256 519000000 Hz -1 dBmV 44 dB 0 0
16 Locked QAM256 525000000 Hz -1 dBmV 44 dB 0 0
17 Locked QAM256 531000000 Hz -1 dBmV 44 dB 0 0
18 Locked QAM256 537000000 Hz -1 dBmV 44 dB 0 0
19 Locked QAM256 543000000 Hz -1 dBmV 44 dB 0 0
20 Locked QAM256 549000000 Hz -1 dBmV 44 dB 0 0
21 Locked QAM256 555000000 Hz -1 dBmV 44 dB 0 0
22 Locked QAM256 561000000 Hz -1 dBmV 44 dB 0 0
23 Locked QAM256 567000000 Hz -1 dBmV 44 dB 0 0
24 Locked QAM256 573000000 Hz -1 dBmV 44 dB 0 0
25 Locked QAM256 579000000 Hz 0 dBmV 44 dB 0 0
26 Locked QAM256 585000000 Hz 0 dBmV 44 dB 0 0
27 Locked QAM256 591000000 Hz 0 dBmV 44 dB 0 0
28 Locked QAM256 597000000 Hz 0 dBmV 44 dB 0 0
29 Locked QAM256 603000000 Hz 0 dBmV 44 dB 0 0
30 Locked QAM256 609000000 Hz 0 dBmV 44 dB 0 0
31 Locked QAM256 615000000 Hz 0 dBmV 43 dB 0 0
32 Locked QAM256 621000000 Hz 0 dBmV 44 dB 0 0
193 Locked OFDM PLC 957000000 Hz -1 dBmV 42 dB 2861410 0

 

 

Upstream Bonded Channels
Channel ID Lock Status US Channel Type Frequency Width Power
1 Locked SC-QAM 16400000 Hz 6400000 43.0 dBmV
2 Locked SC-QAM 22800000 Hz 6400000 43.5 dBmV
3 Locked SC-QAM 29200000 Hz 6400000 43.5 dBmV
4 Locked SC-QAM 35600000 Hz 6400000 43.8 dBmV

A follow-on question for Arris, when can we expect the S33 to receive the necessary firmware / certification from Xfinity for the Next Gen Speed Tier (linked below) so we can stop hearing from support that it’s the modem’s fault?

https://assets.xfinity.com/assets/dotcom/projects/cix-4997_compatible-devices/2023.11.22%20Full%20List%20of%20Compatible%20Devices.pdf

As you are experiencing with slow speed internet connection, I suggest you to check the cable signal levels.

You already shared the cable signal levels and the upstream channels power levels are not in a range which need to be starting from 45dBmV to 51dBmV

 Suggest you to contact your internet service provider to adjust the cable signals or reprovisioning the modem to fix this issue.

Next Gen Speed Tier is not available with S33, but it might get updated in future by your internet service provider.

I’ll ask them again, but they’re adamant that everything is within spec. The upstream power levels actually went down when they replaced the line and I removed a splitter. It used to be 47.5. Xfinity support said the upstream SNR is 40.6 and looked great. I’ll see what they say about increasing the power levels.

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