Re: Netgear C6300v2 - Comcast/Xfinity Speed Problems not WiFi

kpkilburn · ‎2020-03-02

Issue

My C6300/AC1750 cable modem/router (Docsis 3.0) is having constant speed problems on Comcast/Xfinity. WiFi is fine on both 2.4 and 5.0GHz. The issue is with the speed as tested by speedtest.net with a direct wire to the router.

I can reboot the router and get the full speed (~300 Mbps) and both WiFi frequencies have full speed. This lasts a day or so, then the speed drops to about 1 to 1.5 Mbps and remains this way until I reboot the router again.

Background

When I first bought the device, I had the speed problem and nothing I did resolved it. An Xfinity tech checked everything and all was ok except for a configuration (?) file that he had pushed to the device. This resolved the problem and brought it up to full speed.

About a week later, the speed issue returned. I was (and still am) able to do a temporary fix by rebooting the device. I even reloaded it to factory settings. This lasted longer--about 3 days--but the speed issue returned again.

I originally had Xfinity's device and never had any problem with it.

Subsequent calls to tech support yielded nothing useful. They said my device was bad and there was nothing they could do.

Questions

Can a modem/router's hardware fail in this manner? It just seems unusal to me that it would work, just at a lower speed.

I'm guessing that this is a software configuration issue with something I can't see (like that configuration file?).

Any ideas on how to fix it myself or what specifically to tell the Xfinity techs to get them to listen to me and fix the problem?

Thanks.

kpkilburn · ‎2020-03-10

Thanks for the replies. Some were useful, some not. I got a notification that one was accepted as a solution. Not sure how that happens because I didn't do it and it certainly wasn't a "solution". I've called Xfinity and they've agreed to loan me a modem/router free of charge for a few days to test it. I suspect it will work perfectly, but at least I'll be able to compare values of the settings.

View solution in original post

FURRYe38 · ‎2020-03-03

What channels are you using? Auto? Try setting manual channel 1, 6 or 11 on 2.4Ghz and any unused channel on 5Ghz.
Any Wifi Neighbors near by? If so, how many?

Try testing with a different wifi device to compare with...

Ensure WMM is enabled on the modem. If any Beamforming is availalbe, enable this as well. Also set 40Mhz only co-existance.

Has a factory reset and setup from scratch been performed since last update?

kpkilburn · ‎2020-03-03

Thanks for the reply. I appreciate the assistance, but I'm trying to understand what any of this has to do with my problem. I don't mean that to sound antagonistic. I really don't understand why every tech support person I've spoken with starts troubleshooting WiFi with me when the problem exists with a direct line to the router.

When the modem/router is working properly, my WiFi is flawless. From what I can see, there is no problem with WiFi at all.

FURRYe38 · ‎2020-03-04

Has a factory reset and setup from scratch been performed since last update?

Does this happen with a different wired PC or laptop?

Swap LAN cables to compare between modem and PC. CAT6 is recommended.

vkdelta · ‎2020-03-04

Please post your power values and event log.

How often can you see it?

when the speeds are slow, is the wired speeds impacted as well?

kpkilburn · ‎2020-03-04

@FURRYe38 wrote:
Has a factory reset and setup from scratch been performed since last update?

Does this happen with a different wired PC or laptop?
Swap LAN cables to compare between modem and PC. CAT6 is recommended.

Yes, I've done a factory reset several times.

Yes, it happens on different PCs/Macs wired directly into the router with different cables.

When the problem happens, it's system wide--the wired and WiFi connections all drop speed. Upon reboot, they all go back to their normal speeds for awhile then the cycle continues.

kpkilburn · ‎2020-03-04

@vkdelta wrote:
Please post your power values and event log.
How often can you see it?
when the speeds are slow, is the wired speeds impacted as well?

All speeds are impacted--wired and WiFi. I'm having problems posting the logs. Will post later.

kpkilburn · ‎2020-03-05

Startup Procedure
Procedure Status Comment
Acquire Downstream Channel 393000000 Hz Locked
Connectivity State Ok Operational
Boot State Ok Operational
Security Enabled BPI+
IP Provisioning Mode Honor MDD honorMdd(4)
Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables UnCorrectables
1 Locked QAM 256 1 297000000 Hz -2.2 dBmV 38.9 dB 441 0
2 Locked QAM 256 2 303000000 Hz -2.7 dBmV 40.3 dB 414 0
3 Locked QAM 256 3 309000000 Hz -2.9 dBmV 40.3 dB 484 0
4 Locked QAM 256 4 315000000 Hz -2.9 dBmV 40.3 dB 451 0
5 Locked QAM 256 5 321000000 Hz -2.7 dBmV 40.3 dB 487 0
6 Locked QAM 256 6 327000000 Hz -2.5 dBmV 40.3 dB 450 0
7 Locked QAM 256 7 333000000 Hz -2.5 dBmV 40.3 dB 468 0
8 Locked QAM 256 8 339000000 Hz -2.5 dBmV 40.9 dB 553 0
9 Locked QAM 256 9 345000000 Hz -2.4 dBmV 40.3 dB 489 0
10 Locked QAM 256 10 351000000 Hz -2.2 dBmV 40.3 dB 559 0
11 Locked QAM 256 11 357000000 Hz -2.2 dBmV 40.3 dB 562 0
12 Locked QAM 256 12 363000000 Hz -2.7 dBmV 40.3 dB 600 0
13 Locked QAM 256 13 369000000 Hz -3.0 dBmV 40.3 dB 571 0
14 Locked QAM 256 14 375000000 Hz -3.2 dBmV 38.9 dB 593 0
15 Locked QAM 256 15 387000000 Hz -3.5 dBmV 40.3 dB 643 0
16 Locked QAM 256 16 393000000 Hz -3.7 dBmV 40.3 dB 658 0
Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 4 5120 Ksym/sec 16600000 Hz 49.5 dBmV
2 Locked ATDMA 3 5120 Ksym/sec 23000000 Hz 49.5 dBmV
3 Locked ATDMA 2 5120 Ksym/sec 29400000 Hz 49.5 dBmV
4 Locked ATDMA 1 5120 Ksym/sec 35800000 Hz 49.5 dBmV
Current System Time: Thu Mar 5 10:32:33 2020
System Up Time: 21:04:47

kpkilburn · ‎2020-03-05

FOLLOW-UP:

I spoke to Xfinity (again) and the tech said he had found something on their end wrong.

He said there was a setting in the system that indicated I had two modems, not one as it should be. He said he'd seen this problem a lot and assured me that it would definitely fix the problem. After a reboot, the speed was at its advertised rates (whcih it ALWAYS is after a reboot).

A while later, it dropped back down.

Does his diagnosis sound right? Even if so, it apparently wasn't the only problem and didn't fix the speed issue.

kpkilburn · ‎2020-03-05

@vkdelta wrote:
Please post your power values and event log.
How often can you see it?
when the speeds are slow, is the wired speeds impacted as well?

I've posted the event log several times, but it keeps disappearing. Does it contain something that shouldn't be posted? I can't imagine what it would be though!

kpkilburn · ‎2020-03-05

Here is the event log yet again...

Event Log
Clear Log Refresh

Time Priority Description
Mar 02 2020 23:54:16 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Mar 01 2020 22:30:13 Critical (3) No Ranging Response received - T3 time-out
Feb 28 2020 03:14:37 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Feb 28 2020 03:11:21 Error (4) CheckDmgProvision dmg_provisioning process is not running, need to restart.
Feb 28 2020 01:38:07 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Feb 28 2020 01:36:11 Critical (3) No Ranging Response received - T3 time-out
Feb 28 2020 01:36:08 Warning (5) B-INIT-RNG Failure - Retries exceeded
Feb 28 2020 01:34:57 Critical (3) No Ranging Response received - T3 time-out
Feb 28 2020 01:34:41 Critical (3) Unicast Ranging Received Abort Response - initializing MAC
Feb 28 2020 01:34:40 Critical (3) No Ranging Response received - T3 time-out
Feb 28 2020 01:34:39 Warning (5) B-INIT-RNG Failure - Retries exceeded
Feb 28 2020 01:33:36 Critical (3) No Ranging Response received - T3 time-out
Feb 28 2020 01:33:20 Critical (3) Unicast Ranging Received Abort Response - initializing MAC
Feb 28 2020 01:33:19 Critical (3) No Ranging Response received - T3 time-out
Feb 28 2020 01:33:16 Warning (5) B-INIT-RNG Failure - Retries exceeded
Feb 28 2020 01:31:51 Critical (3) No Ranging Response received - T3 time-out
Feb 28 2020 01:31:49 Warning (5) B-INIT-RNG Failure - Retries exceeded
Feb 28 2020 01:30:39 Critical (3) No Ranging Response received - T3 time-out
Feb 28 2020 01:30:22 Critical (3) Unicast Ranging Received Abort Response - initializing MAC
Feb 28 2020 01:30:07 Critical (3) No Ranging Response received - T3 time-out
Feb 28 2020 01:30:05 Warning (5) B-INIT-RNG Failure - Retries exceeded
Feb 28 2020 01:29:12 Critical (3) No Ranging Response received - T3 time-out
Feb 28 2020 01:29:10 Warning (5) B-INIT-RNG Failure - Retries exceeded
Feb 28 2020 01:27:49 Critical (3) No Ranging Response received - T3 time-out
Feb 28 2020 01:27:31 Critical (3) Unicast Ranging Received Abort Response - initializing MAC
Feb 28 2020 01:27:30 Warning (5) B-INIT-RNG Failure - Retries exceeded
Feb 28 2020 01:26:04 Critical (3) No Ranging Response received - T3 time-out
Feb 28 2020 01:26:02 Warning (5) B-INIT-RNG Failure - Retries exceeded
Feb 28 2020 01:24:57 Critical (3) No Ranging Response received - T3 time-out
Feb 28 2020 01:13:04 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out
Feb 28 2020 01:12:11 Warning (5) Lost MDD Timeout
Feb 28 2020 01:12:07 Critical (3) SYNC Timing Synchronization failure - Loss of Sync
Feb 27 2020 19:57:17 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Feb 26 2020 14:40:05 Critical (3) No Ranging Response received - T3 time-out
Feb 25 2020 09:26:29 Warning (5) MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1
Time Not Established Critical (3) No Ranging Response received - T3 time-out
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vkdelta · ‎2020-03-05

your RF line has lot of noise or misconfig on the ISP side.

Too many T3 timeouts and also you are getting B-INIT-RNG failure which is bad. That means device is having trouble bonding.

your US power is high as well.

did ISP inspect your line?

NachoWifi · ‎2020-03-05

Your upstream bonded channels do look a bit bordeline high... staying under 50dBmV is what's acceptable here in the midwest, not sure if it applies everywhere. If you're only using internet service from your ISP and nothing else (no cable boxes or Dish boxes), I would suggest looking around the house or in your utility room for cable splitters. See if you can simplify things with bypassing the cable splitter and with connecting the incoming feed directly to the outlet leading up to the modem. It's going to be that, or it's going to be a bad outside cable to the utility pole.

kpkilburn · ‎2020-03-06

@vkdelta wrote:
your RF line has lot of noise or misconfig on the ISP side.

Too many T3 timeouts and also you are getting B-INIT-RNG failure which is bad. That means device is having trouble bonding.

your US power is high as well.

did ISP inspect your line?

Yes, when I first had the problem right after I got my Netgear modem/router. It worked fine with the Xfinity device. I never really checked the speed because I could stream several devices, download, etc. with no problems and it "seemed" fast.

I"ll have them come back out. I hate Xfinity because they'll charge a service call fee, but they decide that ony after the tech comes out. They couldn't tell me what criteria they use to determine if they charge the fee or not.

kpkilburn · ‎2020-03-06

@NachoWifi wrote:
Your upstream bonded channels do look a bit bordeline high... staying under 50dBmV is what's acceptable here in the midwest, not sure if it applies everywhere. If you're only using internet service from your ISP and nothing else (no cable boxes or Dish boxes), I would suggest looking around the house or in your utility room for cable splitters. See if you can simplify things with bypassing the cable splitter and with connecting the incoming feed directly to the outlet leading up to the modem. It's going to be that, or it's going to be a bad outside cable to the utility pole.

There is one splitter on the outside of the house. The tech checked everything from the pole and throughout the house. I watched him connect a meter, but I didn't write down the numbers he was reading off. He did replace one connector at the pole.

All the tech support seems to think it's configuration issues at the ISP and they "do something" that seems to work (and as I've said, rebooting fixes it very temporariy, so of course it works from their perspective).

kpkilburn · ‎2020-03-10

Thanks for the replies. Some were useful, some not. I got a notification that one was accepted as a solution. Not sure how that happens because I didn't do it and it certainly wasn't a "solution". I've called Xfinity and they've agreed to loan me a modem/router free of charge for a few days to test it. I suspect it will work perfectly, but at least I'll be able to compare values of the settings.

Shurlock3 · ‎2020-03-29

I am having the exact same issue with spectrum cable internet .. and the same issue with techs wanting to trouble shoot the wireless instead of the ethernet. I have experienced in the past week people " calling " themselves engineers that dont even know what i am saying to them when i use simple terms to describe this issue. always the same case " I wanna send out a tech " so they can pass the buck and get back to watching youtube.. for once i would like to speak with a real freaking professional about this issue... I fond more professional responces from my fellow consumer than those engiineers who obviously only got their jobs because they were available to fill a dang seat

tddougla · ‎2020-04-06

I have the same thing going on with Xfinity and they even said the cable modem was for sure to blame or something in my house. I can see the drops on the logs and even Denial of Service hits coming through the ISP. No one that speaks english and with capabilities at Xfinity to share with that I can reach at least. They want me to buy an Xfinity modem which will take away my monitoring capabilities and I'm sure not correct the issue.

FURRYe38 · ‎2020-04-06

Have the ISP check the signal and line quality UP to the modem.
Be sure there are not coax cable line splitters in the between the modem and ISP service box.
Be sure your using good quality RG6 coax cable up to the modem.

@tddougla wrote:
I have the same thing going on with Xfinity and they even said the cable modem was for sure to blame or something in my house. I can see the drops on the logs and even Denial of Service hits coming through the ISP. No one that speaks english and with capabilities at Xfinity to share with that I can reach at least. They want me to buy an Xfinity modem which will take away my monitoring capabilities and I'm sure not correct the issue.