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Voidwalkergirl
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Friday, December 10th, 2021 9:53 AM

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Download speeds: great! Upload speeds: abyssmal... :(

Using a MB8600 (an approved 3p Docsis 3.1 modem). For a long time (in the tune of years), I was getting about 10-12Mbps upload on my current plan.

This past week, I'm averaging most of the time around < 1Mbps (like 0.3 - 0.5).

As a gamer and a WFH employee, I need my upload speeds back...😭

Troubleshooting performed:
- Reboot Modem

- Reboot router (just in case; download speeds are in fact, just fine)

- changed wireless / wired

- tested during various times of day and night

- No listed outages

- tracert capture was inconclusive but it did seem to "struggle" the most between my router/modem and the next few hops along the way to UW (picked somewhere close)

(EDIT: I'm about ready to submit this and a final speed test gave me 11Mbps peak for upload... 🙄)
(EDIT2: And back to <1 Mbps)

Question

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Updated 

3 years ago

 • Edited

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BruceW

Gold Problem Solver

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25.8K Messages

3 years ago

Are you connecting via Wifi or Ethernet? If Wifi, it's best to switch to an Ethernet cable connection if possible for testing. That would allow you to determine whether the problem is the Wifi signal or the link between your modem or gateway and Comcast's network. Network connection problems that affect both Ethernet and Wifi devices are often due to poor coax connections or damaged coax cable, usually in or near your home.

If you want to troubleshoot this yourself, please see Internet Troubleshooting Tips. If you still need help, please post your Internet plan speed and the following information from your modem (from http://192.168.100.1):

  • downstream: power levels, SNR, and error counts
  • upstream: power levels
  • event log, if available (Be sure to remove or blot out any MAC addresses. Forum security processing considers them "personal information" and may prevent the event log from posting if these are present.)

If you can't find the problem or you'd rather have Comcast take care of it, call them at the phone number on your bill or 1-800-Comcast, or use one of the options on https://www.xfinity.com/support/contact-us/. It's not likely they can fix the problem remotely. If not, insist they send a tech out to identify the cause and correct it.

If the tech finds bad coax, splitters, amplifiers, or connections in your home (even if Comcast originally supplied them) you'll probably have to pay for the visit unless you have their Service Protection Plan ( https://www.xfinity.com/support/articles/service-protection-plan, closed to customers that don't already have it). If the trouble is due to a faulty Comcast rental device or anything outside your home you shouldn't be charged.

Note: Be aware that there are 2 kinds of responses in this Forum: Replies and Comments. When you Comment on a post, the author of the post you are Commenting on is notified of your response. But if you Reply, the author of the post you are Replying to is NOT notified and may not be aware of your response.

(edited)

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0

EG

Expert

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105.6K Messages

3 years ago

Start with the modem's signal stats. Perhaps they already are, or they are close to being out of spec and intermittently they go completely of spec. Try getting them here http://192.168.100.1 or here http://10.0.0.1 


Please copy all of the text of the *Downstream Power Level*, the *Upstream Power Level*, and the *SNR* (Signal to Noise Ratio) numbers and paste them into your next post.


What is the exact make and model number of the modem ?

Are there any modem component RF error log entries being shown ? If so, please post them as well in their entirety (copy and paste them, don't post a screenshot) but redact the CM MAC and the CMTS MAC addresses for your privacy. They are considered to be personal information. Personally identifying information is a violation of their forum guidelines. The forum bot will not allow your post to be seen publically.

Please also post (copy and paste) the text output of a traceroute to google.com

1

EG

Expert

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105.6K Messages

@BruceW 

I didn't see your reply before I posted Bruce. We may have both posted at the same time. 😮 😁 

 

(edited)

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? Please mark an Accepted Answer!tick

3 years ago

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Len5

Contributor

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21 Messages

3 years ago

Not sure this will help but recently I was having the same issue, great d/l speed, terrible u/l. After six tech visits, two supervisor visits, and two bucket trucks, the last tech finally figured out it was due to a faulty amplifier in the cable. Tech didn't think we needed it any more so he removed it and wham, everything back to normal. Note: This entire process took about six weeks.

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Voidwalkergirl

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5 Messages

@Len5 Funny enough, there IS a amplifier in the garage but it is currently not connected to anything. It's straight from the "ground" to the modem (AFAIK)

3 years ago

0

Voidwalkergirl

Visitor

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5 Messages

3 years ago

 Downstream Bonded Channels  
  
   Channel Lock Status Modulation Channel ID Freq. (MHz) Pwr (dBmV) SNR (dB) Corrected Uncorrected
   1 Locked QAM256 4 441.0 2.5 44.1 335 56
   2 Locked QAM256 1 423.0 2.8 44.2 323 49
   3 Locked QAM256 2 429.0 2.7 44.2 368 56
   4 Locked QAM256 3 435.0 2.5 44.1 371 52
   5 Locked QAM256 5 447.0 2.4 44.1 349 56
   6 Locked QAM256 6 453.0 2.7 44.2 357 27
   7 Locked QAM256 7 459.0 2.8 44.2 350 38
   8 Locked QAM256 8 465.0 3.0 44.5 328 59
   9 Locked QAM256 9 471.0 2.7 44.3 345 3
   10 Locked QAM256 10 477.0 2.8 44.3 330 55
   11 Locked QAM256 11 483.0 2.5 44.1 328 41
   12 Locked QAM256 12 489.0 2.6 44.2 316 53
   13 Locked QAM256 13 495.0 2.1 43.9 377 48
   14 Locked QAM256 14 507.0 1.8 43.9 341 1
   15 Locked QAM256 15 513.0 1.8 43.9 264 19
   16 Locked QAM256 16 519.0 1.6 43.8 258 43
   17 Locked QAM256 17 525.0 1.8 43.7 281 22
   18 Locked QAM256 18 531.0 1.7 43.5 282 31
   19 Locked QAM256 19 543.0 1.5 43.7 295 51
   20 Locked QAM256 20 549.0 1.5 43.7 310 56
   21 Locked QAM256 21 555.0 1.6 43.7 337 12
   22 Locked QAM256 22 561.0 1.8 43.9 333 0
   23 Locked QAM256 23 567.0 1.9 43.5 264 20
   24 Locked QAM256 24 573.0 1.8 43.6 284 0
   25 Locked QAM256 25 579.0 1.5 43.5 250 0
   26 Locked QAM256 26 585.0 1.2 42.5 303 2
   27 Locked QAM256 27 591.0 0.8 42.5 278 36
   28 Locked QAM256 28 597.0 0.9 43.0 283 56
   29 Locked QAM256 29 603.0 1.0 43.2 232 54
   30 Locked QAM256 30 609.0 1.2 43.4 301 29
   31 Locked QAM256 31 615.0 1.3 43.4 323 3
   32 Locked QAM256 32 621.0 1.2 43.3 282 0
   33 Locked OFDM PLC 193 722.0 -0.7 42.5 68385 0


   Upstream Bonded Channels  
  
   Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV)
   1 Locked SC-QAM 17 5120 35.6 35.5
   2 Locked SC-QAM 18 5120 29.2 34.5
   3 Locked SC-QAM 19 5120 22.8 37.0
   4 Locked SC-QAM 20 5120 16.4 37.0
   5 Locked SC-QAM 21 2560 40.4 37.0

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Voidwalkergirl

Visitor

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5 Messages

3 years ago

Time  Priority  Description 
16:53:03   Critical (3)   No Ranging Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Wed Nov 24 2021
8:57:49 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Fri Nov 26 2021
13:14:01   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Sat Nov 27 2021
13:41:34 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Sun Nov 28 2021
22:34:51   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Sun Nov 28 2021
1:34:50 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Mon Nov 29 2021
18:53:00   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Wed Dec 1 2021
15:08:46 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 2 2021
15:09:17   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 2 2021
15:16:01 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 2 2021
15:46:32   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 2 2021
15:47:02 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 2 2021
15:58:46   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 2 2021
20:33:51 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 2 2021
23:39:37   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 2 2021
18:29:43 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Fri Dec 3 2021
20:03:07   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Sat Dec 4 2021
Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=<redacted>;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
21:43:41   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Sun Dec 5 2021
5:29:17 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Mon Dec 6 2021
9:33:49   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Mon Dec 6 2021
Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=<redacted>;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
23:15:55   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Wed Dec 8 2021
2:32:26 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 9 2021
5:24:48   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 9 2021
Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=<redacted>;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
14:50:53   Critical (3)   No Ranging Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 9 2021
17:23:36 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 9 2021
18:41:03   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 9 2021
Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=<redacted>;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
Time Not Established   Notice (6)   Honoring MDD; IP provisioning mode = IPv6
1:11:09 Notice (6) DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1.;CM-MAC=<redacted>;CMTS-MAC=<redacted>;CM-QOS=1.1;CM-VER=3.1;
Fri Dec 10 2021

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0

BruceW

Gold Problem Solver

 • 

25.8K Messages

3 years ago

The downstream power levels and SNR, and the upstream power levels all look OK, but the event log entries indicate the modem is having problems communicating with Comcast's network. You should have one of their premise techs out to diagnose and correct the problem.

(edited)

2

Voidwalkergirl

Visitor

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5 Messages

@BruceW

That was kinda my thinking as well... @Xfinity Support could probably get that ball rolling, right?
 

3 years ago

0

CCAbbie

Problem Solver

 • 

1.4K Messages

@Voidwalkergirl Hello and thank you for taking the time to communicate via the Xfinity Communities forum. I am sorry to hear you are experiencing these issues. I can assist with getting a tech scheduled. 

 

Please send a private message by clicking the direct messaging chat icon in the upper right corner of the page, click on the pen and paper icon, then enter “Xfinity Support” in the “To” section. Please include your name and address and I'll be happy to help.

I no longer work for Comcast.

3 years ago

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