• Now's your chance win big! Join our community and get entered to win a RTX 2060 GPU, plus more! Join here.

    Pi Cast Episode 3 streams live on Tuesday, August 4th at 2:30 pm ET (7:30 PM BST). Watch live right here!

    Catch Scharon on the Tom's Hardware Show live on Thursday, August 6th at 2:00 pm ET (7:00 PM BST). Click here!

[SOLVED] I'm having constant t3 modem resets, looking for some insight

Spawnova

Honorable
Nov 18, 2013
23
0
10,510
0
I've always had some internet problems at my current location but after asking comcast to send a guy out and fix it a couple months ago it just became insanely worse, I get about 20-40 disconnects every day, most of them are t3 timeouts, and a few are t4, here's a screenshot of the event log - View: https://imgur.com/l9u6S9U

and here's a screenshot of my connection page, the uptime is exactly 1 day for this screenshot - View: https://imgur.com/7YskV5T


Now the problem seems to be an issue with my upstream power levels (dbmv), my modem (motorola 7700) suggests an ideal range to be 37-48, and to always be below 54 and all 4 channels should only be less than 3 dbmv apart from eachother.
Currently, my dbmv is all over the place, spiking constantly, when it hits 54 my modem performs a reset.

I wrote a program to log the current upstream dbmv and the corrected/uncorrected packets and display them in a graph, here's a screenshot of that - View: https://imgur.com/l9SsMlV

the white lines on the bottom are corrected packets, the pink lines are uncorrected, their length does not match the number on the left, it's just so i can see when I'm dropping packets.
when the lines go off the window, it's because for a few seconds my modem displays wrong power levels, but I keep it because it's a good visual cue that the modem reset, in that image I disconnected about 10 times.

So I'm hoping someone with more knowledge can help me out here and suggest maybe what I should so, I've gotten a Comcast technician to visit about 6 times in the last year, and every time they say the problem is something different, try and fix it, and it changes nothing, I don't think the problem is on my end but I don't really know.

Also my main coaxial cable coming from the pole to the house currently is going through a tree, with a branch pushing the cable to about a 60 degree angle, not sure if that could be a problem either, wondering what others think.

If you need any more information let me know, like I said I'm a noob here and I would really appreciate some help =P
 
The tree will make no difference as long as the cable is not damaged. It could eventually cause damage.

The numbers going over 50 is going to be your issue. It gets fairly unstable especially when you see stuff like 51 or higher. The ISP should also see this and agree it is a problem. You downstream power is a bit high sometime they put a attenuate in the line to drop this number a bit.

I would put the modem where the cable comes into the house with no splitters connected. This is mostly to prove to the ISP it is not the cables in your house.

The meters they use to test the signals are much more senitive than the modem so they should be able to find the problem.
 
Reactions: Spawnova

Spawnova

Honorable
Nov 18, 2013
23
0
10,510
0
Thanks, I will try that! My problem now is just getting a guy over here to show him the issue, since Comcast really loves this corona virus stuff atm, it gives them a perfect excuse not to send people over, so it's extremely hard to get a technician. =[
 

Spawnova

Honorable
Nov 18, 2013
23
0
10,510
0
Just an update, I removed the cable from the splitter and attached it directly to the barrel connector, and I'm not longer getting crazy upstream spikes
This is what my power looks now - View: https://imgur.com/EDGW5N9


My downstream power has raised to about 11-12 dbmv, but according to my modem manual, a value up to +15 is acceptable

I'm going to keep monitoring it for next few days but so far massive improvement, thanks for the tip, I wouldn't have thought removing a splitter would actually decrease upstream power, but it seems to be fine now. =D
 
This is partially why the ISP always blames the cable in the house....sometimes its true.

The upstream power work backwards to what you would think it does. What the ISP equipment does is if it is having issues hearing your modem it tells the modem to increase the transmit power on the upstream. Since you only know what you transmit you don't really know what the ISP is getting.

Although there are some levels that are considered too low the upstream power will be set to the lowest level that the ISP can get a good signal from you. When it is too high it is a indication that the ISP has requested you transmit higher. Lot of things can cause it but splitter and bad cables are common.
 

ASK THE COMMUNITY