Question Poor Network Performance

Oct 10, 2020
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I recently started having issues with my upload speeds. I have a SB6141 modem and a 150 / 10 Mbps plan with Cox. Intermittently throughout the day my upload speeds drop to roughly 0.15Mbps, on every wireless and wired device. Otherwise I have had solid service for a few years at advertised speeds. Here's what I have tried to troubleshoot the issue:

Power cycle modem / router
Ensure coaxial connections are secure
Check modem signal diagnostics (see below)
Update router firmware
Disconnect all devices from router and try individual devices on ethernet and wifi to ensure no bandwidth hogging is occurring
Watch router upload traffic counter when issue is ongoing
Bypass router and connect PC ethernet directly to modem
Check packet loss to router/modem (OK)
Check packet loss to other servers (I get about 4% when it's being super laggy, but oddly the ping is always low < 40ms)

I have no cable TV or splitters in the house. My issue has persisted no matter the steps I tried above. For a bulk amount of the day it's OK and not noticeable, but when it starts lagging it makes my internet almost unusable. It also oddly occurs most often at night. I have contacted cox three times and each time they say that there are no known outages in my area, and everything appears fine. Towards the end of the conversation they try to sell me on buying a new modem and router from them. On my last call with cox they said they could send a technician, but if they find nothing wrong I will be charged $75+ taxes and fees for the service call. I am afraid he won't find any issue with my connection because it is so intermittent.

Based on what I have checked, do you think the issue lies on my end or somewhere upstream?


DownstreamBonding Channel Value
Channel ID3334353637383940
Frequency357000000 Hz363000000 Hz369000000 Hz375000000 Hz381000000 Hz387000000 Hz393000000 Hz399000000 Hz
Signal to Noise Ratio38 dB38 dB39 dB38 dB39 dB38 dB36 dB37 dB
Downstream ModulationQAM256QAM256QAM256QAM256QAM256QAM256QAM256QAM256
Power Level
The Downstream Power Level reading is a snapshot taken at the time this page was requested. Please Reload/Refresh this Page for a new reading​
5 dBmV6 dBmV6 dBmV6 dBmV5 dBmV3 dBmV0 dBmV1 dBmV



UpstreamBonding Channel Value
Channel ID3421
Frequency32200000 Hz38600000 Hz25800000 Hz19300000 Hz
Ranging Service ID574574574574
Symbol Rate5.120 Msym/sec5.120 Msym/sec5.120 Msym/sec5.120 Msym/sec
Power Level44 dBmV43 dBmV43 dBmV43 dBmV
Upstream Modulation[3] 16QAM
[3] 64QAM
[3] 16QAM
[3] 64QAM
[3] 16QAM
[3] 64QAM
[3] 16QAM
[3] 64QAM
Ranging StatusSuccessSuccessSuccessSuccess



Signal Status (Codewords)Bonding Channel Value
Channel ID3334353637383940
Total Unerrored Codewords39662895283966297706396630885639662804763966275344396627618439662779423966277124
Total Correctable Codewords223568154611518573486
Total Uncorrectable Codewords605613767154263967613701509
 
The values look pretty good and your errors are about what you see on any connection. These counters are not reset very often so you always have some.

I would see if there is anything in the log. Again you will always see some garbage errors but what you are looking for is ones that occur about the time you are seeing a problem.

Intermittent problems are extremely hard to find. It is unlikely it is a cabling issue since those issues tend to be constant and increase as load increases.

I would first run a tracert to 8.8.8.8 just to get the ip of the router in the path. Next open a number cmd windows and run ping in the background. You want to have ping run to hop 1 (your router) hop 2 (the ISP first router) and some ip like 8.8.8.8. You can do other ones but the deeper they are in the network the less likely you will get it fixed.

What you want to do is when you are detecting errors quickly switch to the cmd windows and see which if any have problems. No errors on hop 1 but errors on hop 2 would indicate it is in the connection coming to your house.
 
Reactions: big-plans
Excellent diagnostic work. The key one for me is connecting systems directly to the modem and you still have issues--this points to an isp issue.

The way around the technician issue is to use their modem/whatever for a month and then call them with issues. It's their equipment, their connection and if it's not right, they are liable. I would also ask for credits on the outages.

Worse case as I've seen this before with a bad isp with an issue that went on for years, just get another provider and disconnect. Then after a year or so sign on again and make sure they get it right from day one.
 
Reactions: big-plans
Oct 10, 2020
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As an update I have icmp pinged hop2 (default settings) with the following result:

Packets: Sent = 351, Received = 340, Lost = 11 (3% loss),
Approximate round trip times in milli-seconds:
Minimum = 7ms, Maximum = 33ms, Average = 10ms

At other times I have used packetlosstest.com with varying settings and have had packetloss as high as 15%. I think if I were patient enough the cmd prompt method would eventually converge closer to this number.

Thank you for your responses. I now feel confident that I'm not missing any major troubleshooting steps and I have scheduled a technician to come out next week. I'm hoping for a simple fix nearby my house.
 

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