Question Unreliable connection / high packet loss / high uncorrectables / Cox

May 17, 2021
5
2
15
0
A couple of months ago we began having significant problems with our previously reliable internet. Cox tech support told me that the signal looked "weak" on their end and so sent a tech. The tech confirmed the signal was bad but thought it was because of a problem with the box (I think he called it a tap) on the pole outside. But because he didn't have time to fix it, he put in an amplifier, called a supervisor, told me the supervisor would call me back, and left.

Supervisor never called.

Fast forward a week, the problem remains, and I call tech support again. They tell me someone already went to fix the box/tap. But the problem remains, so a second tech comes. The second tech confirms problems with the signal, replaces some connectors outside, including an old one from an old telephony service.

The problem gets better for a week or so, but is now back. Packet loss ranges from 0 to as high as nearly 50%. I even got a few "PING: transmit failed. General failure." at one point.

In the course of troubleshooting, I check the modem signal levels myself, and see the below. From what I can gather, the power and SNR levels are OK, but the corrected/uncorrectables are extremely high. Googling suggests installing a MoCA filter might help, so I've ordered some. I've also ordered a new cable modem.

ChannelLock StatusModulationChannel IDFrequencyPowerSNRCorrectedUncorrectables
1Locked256QAM21903.00 MHz-2.60 dBmV32.96 dB346918115134936
2Locked256QAM1783.00 MHz6.40 dBmV37.64 dB148312832542
3Locked256QAM2789.00 MHz6.80 dBmV38.61 dB3403212
4Locked256QAM3795.00 MHz6.60 dBmV37.64 dB2752145
5Locked256QAM4801.00 MHz7.50 dBmV38.61 dB2372153
6Locked256QAM5807.00 MHz7.10 dBmV38.61 dB2042055
7Locked256QAM6813.00 MHz6.40 dBmV37.64 dB4013138
8Locked256QAM7819.00 MHz6.10 dBmV37.64 dB3912193
9Locked256QAM8825.00 MHz5.20 dBmV37.64 dB1564040825
10Locked256QAM9831.00 MHz4.30 dBmV36.61 dB195030640385
11Locked256QAM10837.00 MHz3.10 dBmV36.39 dB81407461393
12Locked256QAM11843.00 MHz2.40 dBmV35.78 dB9542265462733
13Locked256QAM12849.00 MHz1.70 dBmV35.78 dB95012122
14Locked256QAM13855.00 MHz0.40 dBmV34.93 dB388512945
15Locked256QAM14861.00 MHz0.10 dBmV34.48 dB832812831
16Locked256QAM15867.00 MHz-0.40 dBmV34.35 dB1214723055
17Locked256QAM16873.00 MHz-0.20 dBmV34.35 dB1068642151
18Locked256QAM17879.00 MHz-0.40 dBmV34.35 dB1012842164
19Locked256QAM18885.00 MHz-0.10 dBmV35.08 dB639322240
20Locked256QAM19891.00 MHz-0.80 dBmV34.35 dB954363125
21Locked256QAM20897.00 MHz-1.60 dBmV33.49 dB1251143167
22Locked256QAM22909.00 MHz-3.50 dBmV32.24 dB1344085579337484
23Locked256QAM23915.00 MHz-3.90 dBmV31.99 dB1524573595548338
24Locked256QAM24921.00 MHz-4.70 dBmV31.34 dB1519120595274441
25Locked256QAM25927.00 MHz-4.80 dBmV31.60 dB500465560
26Locked256QAM26933.00 MHz-5.20 dBmV31.20 dB7313242717
27Locked256QAM27939.00 MHz-6.50 dBmV29.70 dB17701572384
28Locked256QAM28945.00 MHz-7.40 dBmV29.30 dB52577922836
29Locked256QAM29951.00 MHz-7.40 dBmV29.10 dB79230581914
30Locked256QAM30957.00 MHz-6.90 dBmV29.50 dB37699933038
31Locked256QAM31963.00 MHz-7.50 dBmV29.10 dB75012712645
32Locked256QAM32969.00 MHz-7.70 dBmV28.90 dB221423631727


Upstream Bonded Channels
ChannelLock StatusUS Channel TypeChannel IDSymbol RateFrequencyPower
1LockedATDMA15120 kSym/s19.10 MHz38.00 dBmV
2LockedATDMA62560 kSym/s14.30 MHz38.50 dBmV
3LockedATDMA45120 kSym/s38.40 MHz39.50 dBmV
4LockedATDMA35120 kSym/s32.00 MHz39.00 dBmV
5LockedATDMA25120 kSym/s25.60 MHz39.00 dBmV

Any insight into how to further troubleshoot would be greatly appreciated.

Thanks!
 
You should not need a moca filter unless you actually run moca in your house. Now a neighbor could be injecting moca into the network but that would mess up everyone around you, still moca is designed to coexist with most cables systems.

What looks bad is power levels. The indivual numbers are not way out of range but generally you see all of them about the same value. In your case you have a bunch with positive db and a bunch with a similar negative db.

There is not much you can do this is many times outside your house. All you could try is to replace any cables in your house. I would connect the modem as close as possible to where the cable comes in with no splitters and see if the numbers are any different.

You might see errors in the log also but again there is not much you can do about it the ISP needs to fix it.
 
Reactions: wptlrn and SamirD
May 17, 2021
5
2
15
0
Thank you!

I just plugged in a new modem, have been using it for about 15-30 minutes, and the connection seems to be better--see screenshot here. Could it just be that the modem, which was purchased in 2018, needs to be replaced?

If the issue comes back, I will definitely try plugging in the modem closer to the source. It's an old house (relatively new to us) and I wouldn't be surprised if the cabling is janky.
 
Last edited:

kanewolf

Titan
Moderator
Thank you!

I just plugged in a new modem, have been using it for about 15-30 minutes, and the connection seems to be better--see screenshot here. Could it just be that the modem, which was purchased in 2018, needs to be replaced?

If the issue comes back, I will definitely try plugging in the modem closer to the source. It's an old house (relatively new to us) and I wouldn't be surprised if the cabling is janky.
Running a coax across the floor directly to the outside of the house is the best way to eliminate in-house coax.
Some of your channels have a -7db signal. That is kind of low. Your signal variability is also pretty wide (+7db to -7db). You could definitely have some in-house cabling problems.
 
Reactions: SamirD and wptlrn

gggplaya

Distinguished
You lose I think 3.5db of signal for every split in your house. So if you have a 2 way splitter, you lose 3.5db. If you have a 3 way splitter you lose 7db etc...

If you do not have cable TV, you should plug your cable modem directly into the line coming into the house. Leave out any splitters.

If you do have cable TV, get a 2 way splitter. Split the line coming into your house with 1 of those into your modem. For cable tv, you can split the other line with another multisplitter to all your outlets.
 
Reactions: SamirD and wptlrn
May 17, 2021
5
2
15
0
Thanks everyone. I investigated the lines in my basement and am reasonably confident there's no splitter. I've ordered a long new RG6 cable and will try directly connecting to the line coming into the house and will update this with the results.
 
Keep in mind that you won't be able to fix marginal signal issues and really need the isp to fix that at the source. Your solution might work for a while and then when signal goes out of spec further, it will break again.
 

gggplaya

Distinguished
Thanks everyone. I investigated the lines in my basement and am reasonably confident there's no splitter. I've ordered a long new RG6 cable and will try directly connecting to the line coming into the house and will update this with the results.

This is all you can do. Like SamirD says, if what you've down here doesn't fix the problem. The rest is all up to the ISP to fix.
 
Reactions: SamirD
May 17, 2021
5
2
15
0
So I've now attached a new RG6 cable directly to the line coming into the house. (It's actually slightly attenuated, as the line coming into the house is first routed to another section of the basement to ground the line, before making a u-turn back to the initial point of entry, at which point it's connected to the internal wiring that goes through the wall into my office, which is on the second floor. It's that latter connection that I disconnected. Now, as a temporary measure, the line goes through the window to connect my modem with the grounded line.)

It's been nearly 24 hours and my signals now look like this. The 800 MHz signals are still significantly lower than the 400 MHz ones, but in both absolute and relative terms things seem to have improved. Certainly, the internet connection has been stable. Safe to say this is evidence that the main culprit was the interior cabling? Or, do these figures suggest that there are still issues that might still eventually cause problems?

Thanks everyone for all your help so far!
 
Reactions: SamirD
Now you have me very confused. This almost looks like a different internet connection.

The first is using 32 channels and the second is using 24 channels. The first group of channels are the same but then one modem uses 900mhz and the other 300/400 mhz.

This in some ways would be what I would suspect if a ISP supported different types of docsis connections. What is also strange is the signal levels on the first group of channels is much less it should be better if there is less cable. The number overall are a little better because they are closer but the ones that go to -10 are marginal.

So maybe explain again what you changed.
 
Reactions: SamirD and wptlrn
May 17, 2021
5
2
15
0
Now you have me very confused. This almost looks like a different internet connection.

The first is using 32 channels and the second is using 24 channels. The first group of channels are the same but then one modem uses 900mhz and the other 300/400 mhz.

This in some ways would be what I would suspect if a ISP supported different types of docsis connections. What is also strange is the signal levels on the first group of channels is much less it should be better if there is less cable. The number overall are a little better because they are closer but the ones that go to -10 are marginal.

So maybe explain again what you changed.
Yes, I've changed a few things since the OP.

1. Installed a new modem. Previous one was Arris SB6190. Now I am trying a Motorola MB7621.

2. Removed an amplifier that a Cox tech had previously installed to try to ameliorate the problem.

3. Installed a new RG6 cable to replace in-wall cabling. Now the setup looks like this: Cox's outside line to a basement wall hole <connector 1> line running through basement wall hole to ground block in other part of basement <ground block 2> line back to outside through basement wall hole <connector 3> new RG6 line to modem through second floor window. (Connectors 1 and 3 are female-to-female connectors like this one. Ground block 2 is a ground block like this one. The only aspect of this setup I've changed is the last step. Previously, the line went from connector 3 BACK through the basement wall hole and then through the wall up to the second floor office's wall jack. Now, instead of making that u-turn, it goes up to the office through the window.)
 
Reactions: SamirD
Maybe connect it back to the cable that is not running though the window just to see if you get a usable connection since re running the cable correctly is going to be some effort.

With this many things change it is hard to say which fixed it. The change in the radio frequencies alone is a big difference since cable tends to pass the lower frequencies better.

If you are getting the speed you pay for on the "new" modem using that modem is likley ok. Many times you need to use the ones with 32 channels if you are getting gigabit service from the ISP.
 
Reactions: SamirD and wptlrn

gggplaya

Distinguished
Those inline grounding blocks are fine, as long as it's not a multi-way splitter. The signal loss is negligible. The extra length looping down to the basement and back up should also be negligible as longs as it's really copper. If it's CCA cable, I don't know, I personally don't use the stuff, but even that should be ok.
 
Reactions: wptlrn
So I've now attached a new RG6 cable directly to the line coming into the house. (It's actually slightly attenuated, as the line coming into the house is first routed to another section of the basement to ground the line, before making a u-turn back to the initial point of entry, at which point it's connected to the internal wiring that goes through the wall into my office, which is on the second floor. It's that latter connection that I disconnected. Now, as a temporary measure, the line goes through the window to connect my modem with the grounded line.)

It's been nearly 24 hours and my signals now look like this. The 800 MHz signals are still significantly lower than the 400 MHz ones, but in both absolute and relative terms things seem to have improved. Certainly, the internet connection has been stable. Safe to say this is evidence that the main culprit was the interior cabling? Or, do these figures suggest that there are still issues that might still eventually cause problems?

Thanks everyone for all your help so far!
Well, you have zero correctables and uncorrectables so that's super. Now I'd run packetlosstest.com and see if you have any more loss. If not, run fast.com and dslreports.com/speedtest and if those are okay then I think you've found the culprit.
 

ASK THE COMMUNITY

TRENDING THREADS