Community Forum

Intermittent drops, slow speeds

Highlighted
New Poster

Intermittent drops, slow speeds

My service was working ok but then a few weeks ago I started getting frequent intermittent drops.  Also, my speeds are mostly below 100 Mbps (I'm on the 300 Mbps plan). I've pasted the data from the gateway below. To me, it looks like a comcast network issue: channels 1, 21, and 22 have a signal to noise ratio that is too low (<35 dB), which is confirmed by the large number of uncorrected codewords.  Is this a correct diagnosis? How do I get this fixed? Based on past experience, the comcast reps will just tell me to reboot the modem if I call.  Which I've done multiple times, but then the intermittent drops start again.  Thanks for the help. 

 

IndexLock StatusFrequencySNRPower LevelModulation
Downstream
Channel Bonding Value
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Not Locked
Not Locked
Not Locked
Not Locked
Not Locked
Not Locked
Not Locked
Not Locked
627.00 MHz
633.00 MHz
639.00 MHz
645.00 MHz
651.00 MHz
657.00 MHz
663.00 MHz
669.00 MHz
675.00 MHz
681.00 MHz
687.00 MHz
693.00 MHz
699.00 MHz
705.00 MHz
711.00 MHz
717.00 MHz
723.00 MHz
729.00 MHz
735.00 MHz
741.00 MHz
747.00 MHz
753.00 MHz
759.00 MHz
765.00 MHz
 
 
 
 
 
 
 
 
34.63 dB
38.61 dB
38.98 dB
40.37 dB
40.95 dB
40.37 dB
40.95 dB
40.37 dB
38.98 dB
38.98 dB
40.37 dB
40.95 dB
40.37 dB
40.37 dB
38.98 dB
40.37 dB
38.98 dB
36.39 dB
36.61 dB
38.98 dB
32.24 dB
31.40 dB
40.37 dB
40.37 dB
 
 
 
 
 
 
 
 
5.60 dBmV
5.90 dBmV
6.20 dBmV
6.10 dBmV
6.40 dBmV
6.80 dBmV
6.60 dBmV
5.90 dBmV
5.80 dBmV
5.80 dBmV
5.90 dBmV
6.10 dBmV
5.90 dBmV
6.10 dBmV
6.50 dBmV
7.10 dBmV
6.30 dBmV
5.60 dBmV
5.30 dBmV
6.00 dBmV
6.80 dBmV
6.90 dBmV
6.70 dBmV
6.30 dBmV
 
 
 
 
 
 
 
 
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
 
 
 
 
 
 
 
 
IndexLock StatusFrequencySymbol RatePower LevelModulationChannel Type
Upstream
Channel Bonding Value
1
2
3
4
5
6
7
8
Locked
Locked
Locked
Locked
Not Locked
Not Locked
Not Locked
Not Locked
23.70 MHz
17.30 MHz
30.10 MHz
36.50 MHz
 
 
 
 
5120 KSym/s
5120 KSym/s
5120 KSym/s
5120 KSym/s
 
 
 
 
48.25 dBmV
47.00 dBmV
48.75 dBmV
49.50 dBmV
 
 
 
 
64 QAM
64 QAM
64 QAM
64 QAM
 
 
 
 
DOCSIS2.0 (ATDMA)
DOCSIS2.0 (ATDMA)
DOCSIS2.0 (ATDMA)
DOCSIS2.0 (ATDMA)
 
 
 
 
Unerrored CodewordsCorrectable CodewordsUncorrectable Codewords
CM Error Codewords
249299187
404288489
404302252
404301999
404298667
404306253
404292395
404308131
404302075
404290131
404309997
404311613
404305650
404313292
404296166
404317469
404316854
403875317
404244887
404322398
30938337
42028513
404325575
404329493
0
0
0
0
0
0
0
0
480574
21
407
0
0
0
0
0
0
0
0
0
0
0
0
3
0
206073
66961
0
2294858
897061
0
0
0
0
0
0
0
0
0
0
1187010
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
221298
9417
0
1103154
948606
0
0
0
0
0
0
0
0
0
0
 
Highlighted
Expert

Re: Intermittent drops, slow speeds

Yes. You are correct. And the upstream power is on the high side and it may be intermittently fluctuating even higher to out of spec levels. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In a self troubleshooting effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage types like GE, RadioShack, RCA, Philips, Leviton, Magnavox, and Rocketfish from big box stores like Home Depot, Lowes, Target, Wal-Mart etc. Splitters should be swapped with known to be good / new ones to test

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two way splitter connected directly off of the drop from the street/pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed, and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.



I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
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!
Highlighted
New Poster

Re: Intermittent drops, slow speeds

Thank you.  There was a second splitter in the path and removing it seems to have fixed the problem - no more intermittent drops and the SNR is now over 35 dB on all channels.  Unfortunately that second splitter is needed to get video to our second television, so fixing the Internet means I can't use that TV. There's no easy way  to rewire so that the modem is served by one branch off the remaining splitter and both TVs are served off the second branch.  Also, I don't know why the setup worked for a long time with the second splitter but then stopped working. I'll try replacing the second splitter with a new one and new cables and see if that works.  Thanks again for your help. 

Highlighted
Regular Contributor

Re: Intermittent drops, slow speeds

I have had splitters go bad more then a few times, replaced them and everything came back to life

Highlighted
Expert

Re: Intermittent drops, slow speeds

You may want to get a tech out to investigate / correct the problem. Good luck !



I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
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!