J

Visitor

 • 

2 Messages

Thu, Sep 16, 2021 6:34 PM

Recurring loss of upload bandwidth during specific time range at night

I am currently subscribed at the 1200/(35) Mbps plan and live in a taller apartment building. Since moving in last month, I have been having consistent nightly internet issues from approximately 6:00pm to 5:00am - during these night hours, upload speeds will degrade to <0.3 Mbps, low enough to effectively time out all outbound requests. Download speeds oddly are unaffected, and when a Xfinity/Fast.com/SpeedTest.net/Google speed test does execute, I see 300Mbps+ download speeds (and <0.3Mbps upload). Despite this, without upload bandwidth the internet is unusable. I have worked with the two Xfinity technicians so far in attempting to diagnose the issue but that has been unfruitful.

PingPlotter graph to show the recurring nature of the timeouts/packet loss during the night hours.


I have tested different modems (S33, xFi Gateway, SB8200) different computers, different Ethernet cables, different power outlets, and technicians have checked signal integrity between my building floor's tap and the coaxial cable in the apartment during regular business hours - all seemingly clean with no signs of noise or ingress. They have mentioned that power levels were high at the tap, but should level off once in my apartment. I am not sure if other residents on the same my floor's tap are experiencing similar issues at night. What is frustrating is that during the day (5:00am-6:00pm) internet speeds are nominal (1300Mbps down, although upload always only caps at 20Mbps). Only after these hours does it degrade, and technicians are unavailable outside of business hours, so they are unable to see the issue firsthand.

Is it possible that some damage has occurred to the line into my apartment, and the temperature fluctuation of day and night exacerbates the issue - during the evening my upstream power levels are about +1 to +2dBmV from what is shown below. Another suspicion I have is that an automatic power source of some sort (timed street/building lamp?) is feeding noise into my unit’s line during these hours. 

I appreciate having techs sent over to inspect but I feel like their time is wasted when they do not see the issue firsthand. Any assistance or pointers are greatly appreciated. Kind of getting tired of not having internet at night :)

Edit: The technicians have also said their "network guys" don't see any issues at night.

Arris S33


I see log Event Type Codes 16, 20, 22, and 24 for channel 48, but never any T3/T4 timeouts.

Downstream Bonded Channels
Channel ID Lock Status Modulation Frequency Power SNR/MER Corrected Uncorrectables
20 Locked QAM256 507000000 Hz 1 dBmV 40 dB 1856 0
4 Locked QAM256 405000000 Hz 1 dBmV 41 dB 2399 0
5 Locked QAM256 411000000 Hz 1 dBmV 41 dB 2306 0
6 Locked QAM256 417000000 Hz 1 dBmV 41 dB 2230 0
7 Locked QAM256 423000000 Hz 1 dBmV 41 dB 2177 0
8 Locked QAM256 429000000 Hz 1 dBmV 41 dB 2185 0
9 Locked QAM256 435000000 Hz 1 dBmV 41 dB 2174 0
10 Locked QAM256 441000000 Hz 1 dBmV 40 dB 2131 0
11 Locked QAM256 447000000 Hz 1 dBmV 41 dB 2153 0
12 Locked QAM256 453000000 Hz 1 dBmV 40 dB 2138 0
13 Locked QAM256 459000000 Hz 1 dBmV 40 dB 2050 0
14 Locked QAM256 465000000 Hz 0 dBmV 40 dB 2083 0
15 Locked QAM256 471000000 Hz 1 dBmV 40 dB 2004 0
16 Locked QAM256 477000000 Hz 1 dBmV 41 dB 1973 0
17 Locked QAM256 483000000 Hz 1 dBmV 41 dB 1993 0
18 Locked QAM256 489000000 Hz 1 dBmV 41 dB 2017 0
19 Locked QAM256 495000000 Hz 1 dBmV 40 dB 1972 0
21 Locked QAM256 513000000 Hz 0 dBmV 40 dB 1829 0
22 Locked QAM256 519000000 Hz 0 dBmV 40 dB 1799 0
23 Locked QAM256 525000000 Hz 0 dBmV 40 dB 1769 0
24 Locked QAM256 531000000 Hz 0 dBmV 40 dB 1686 0
25 Locked QAM256 537000000 Hz 1 dBmV 40 dB 1683 0
26 Locked QAM256 543000000 Hz 1 dBmV 41 dB 1633 0
27 Locked QAM256 549000000 Hz 1 dBmV 40 dB 1619 0
28 Locked QAM256 555000000 Hz 2 dBmV 41 dB 1499 0
29 Locked QAM256 561000000 Hz 2 dBmV 41 dB 1546 0
30 Locked QAM256 567000000 Hz 2 dBmV 40 dB 1584 0
31 Locked QAM256 573000000 Hz 2 dBmV 40 dB 1513 0
32 Locked QAM256 579000000 Hz 2 dBmV 40 dB 1508 0
33 Locked QAM256 585000000 Hz 2 dBmV 40 dB 1385 0
34 Locked QAM256 591000000 Hz 2 dBmV 40 dB 1346 0
48 Locked OFDM PLC 850000000 Hz 4 dBmV 39 dB 1036006730 0


 

Upstream Bonded Channels
Channel ID Lock Status US Channel Type Frequency Width Power
1 Locked SC-QAM 16400000 Hz 6400000 48.5 dBmV
2 Locked SC-QAM 22800000 Hz 6400000 49.8 dBmV
3 Locked SC-QAM 29200000 Hz 6400000 50.0 dBmV
4 Locked SC-QAM 35600000 Hz 6400000 51.0 dBmV
5 Locked SC-QAM 40400000 Hz 3200000 51.8 dBmV

xFi Gateway

Downstream
Channel Bonding Value
Index
20
17
18
19
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
Lock Status
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Frequency
507000000
483000000
489000000
495000000
513000000
519000000
525000000
531000000
537000000
543000000
549000000
555000000
561000000
567000000
573000000
579000000
585000000
591000000
597000000
603000000
609000000
615000000
621000000
627000000
633000000
639000000
645000000
651000000
681000000
687000000
693000000
852800000
SNR
38.983261
38.983261
40.366287
38.983261
38.983261
38.983261
38.983261
38.983261
38.983261
38.983261
38.605377
40.366287
38.983261
38.983261
38.983261
38.983261
38.983261
38.983261
38.983261
38.605377
38.605377
38.983261
38.605377
38.605377
38.983261
38.605377
38.605377
38.605377
38.605377
38.605377
38.605377
NA
Power Level
2.900002
3.099998
3.200001
3.099998
2.799999
2.700001
2.900002
3.000000
3.200001
3.400002
3.599998
3.900002
3.799999
3.799999
3.799999
3.700001
3.900002
3.900002
3.799999
3.799999
3.799999
3.799999
3.900002
4.199997
4.000000
3.799999
3.500000
3.599998
3.200001
3.599998
3.799999
NA
Modulation
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
QAM256
OFDM
Upstream
Channel Bonding Value
Index
1
2
3
4
5
Lock Status
Locked
Locked
Locked
Locked
Locked
Frequency
16400000
40400000
35600000
29200000
22800000
Symbol Rate
5120 KSym/sec
2560 KSym/sec
5120 KSym/sec
5120 KSym/sec
5120 KSym/sec
Power Level
47.270599
50.760300
50.270599
49.020599
48.270599
Modulation
64QAM
64QAM
64QAM
64QAM
64QAM
Channel Type
US_TYPE_ATDMA
US_TYPE_ATDMA
US_TYPE_ATDMA
US_TYPE_ATDMA
US_TYPE_ATDMA
CM Error Codewords
Unerrored Codewords
9259
9104
8981
8876
8766
8648
8527
8426
8311
8172
8048
7943
7828
7680
7562
7459
7347
7185
7061
6946
6825
6704
6600
6486
6362
6241
6107
5933
5811
5706
5593
559030611
Correctable Codewords
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3735936685
Uncorrectable Codewords
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3735936685

Responses

EG

Expert

 • 

89.6K Messages

1 m ago

The upstream power is too high. That indicates an upsteam channel / return path line impairment of some sort (possibly noise ingress). You need to get the techs involved again. It's possible that drop amplifier with an *active return* may need to be installed on your line. Lean on them until it gets fixed properly. Good luck !

Visitor

 • 

2 Messages

Thanks @EG

My tech is currently not convinced it is related to high power levels - he says 53 dBmV is in spec.  Is there any way I can schedule a tech take a look at line noise during the night time interruption hours?

Looks like I'll go one more night without internet.

EG

Expert

 • 

89.6K Messages

1 m ago

He's wrong... We've seen it to be always to the contrary here... .No surprise here.... 51 dB is the limit. Comcast turned off the extended upstream power feature a few years ago. I really wish that the techs would get more up to date training than they do..... Don't know how they operate this way.... 35 to 45 dB is the sweet spot. I'm not an employee. I don't know how else to help you.... Sorry...

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