Question Packet Loss Only On Upload

May 27, 2022
Long version:
For about a month I have been experiencing pretty severe packet loss but only on my upload. There was a power surge one day- all of my hardware is plugged into a surge protector- and that night when trying to stream to Twitch I dropped a constant 30% frames. My upstream light would start to blink during the night as well. After two days of that I got a Spectrum tech out to my house and they said their readings were way off from what they were supposed to be and that they would put in a maintenance notice for repairs at the tap. The problem never went away so after a few days I had another tech come out who ran all sorts of tests to rule out my house eventually leading to running a line directly from the ground through my window to my modem while my modem was plugged into a generator. Same issue. He passed it on to a senior tech who came out and ran a new line from the ground to the house and gave me one of their modems to use as well as his phone number to call if the issues persisted. They did, so I called him and he said he'd spoken with his boss and that they both thought it was an area-wide issue and they would call me when it was fixed. It has been over a week with no call and so I had another tech come out today who insisted there was no issue, that all the readings were fine, and that he had no notes of an area-wide issue (and then proceeded to blame everything from my ethernet cables, my neighbors' power, Windows 10, etc).

Short version:
Packet loss on upload after power surge (30% dropped frames when streaming to Twitch, up to 20% packet loss on
Spectrum techs found an issue at the tap and issues persisted after the tap was deemed repaired
Spectrum techs further investigated and said it was an area-wide issue
Most recent spectrum tech says all readings are fine all the way up to my modem
Packet loss continues

What I have done:
Connected my modem directly to the ground cable & a generator to bypass house cables and house power
Was given a new modem by Spectrum to rule out modem issues
Replaced my ethernet cables with brand new cables
Run packet loss tests when directly wired to my router & when directly wired to my modem (no difference in packet loss results)

Packet loss test and settings:
Packet Sizes: 212 and 228 Bytes
Frequency: 60 Pings/Second
Duration: 55 Seconds
Acceptable Delay: 200 Milliseconds

My upload is 10 Mbps.

Most recent packet loss result (with new ethernet cable and directly connected to the modem):

Let me know what other information would be helpful. I appreciate whatever help you can offer since I've now had 4 Spectrum techs out and the most recent one made it pretty clear they're done looking for issues.
Last edited:
Unless you have a expensive generator that runs sine wave power city power will bet better for electronic equipment.

This is one of those things that is extremely hard for a end user to test. What it means is the cable company equipment is having a hard time hearing your equipment. The wires sometimes cause this but it appears they have replaced all the wiring.

From your end everything is going to look fine...more or less. You can receive the data from the cable company and your equipment "thinks" it can send data to the cable company equipment. The data though is actually getting damaged on the way but it is after you have sent it so not much you can do.

A symptom of this tends to be very high signal level on the output/uplink channels in your modem. The exact value depends on encoding being used but in general any number above 50 means there is a issue. What is happening is the cable company equipment is having trouble hearing your modem so it tell it to turn up the transmit power.

Now if your transmit power as well as all the other numbers are ok then it is much harder to say. You can search for the recommended values. The ISP can also see these numbers as well as the numbers on their equipment. If they think everything is fine then I don't know. You have replaced everything on your end so it has to be something on their end.