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Cable Modem errors

Hello everyone,

Trying to troubleshoot an intermittent issue.
Below is the info.

Arris TG862
For a period of about 15 minutes I start seeing slowness and packet loss, speed test show about 11mbps down.
On the modem status page the FEC uncorrectable counter is increasing rapidly.
Then it stops and everything is back to normal, no more slowness and getting the full 50mbps down and can stream test videos without issues.

The tough part is the issue is intermittent, it has happened at noon, early AM, late afternoon.

By the time I am able to get tech support on the line the issue has cleared itself.

Here is the interesting part.
Its only affecting Downstream 3 (549mhz)
Downstream 1, 2, and 4 error counters are always 0.

Is it possible this could be wiring/modem issue when only one channel is having the problem?
I mean, all channels are frequencies over the same cable, so probability says a wiring/modem issue would have all channels affected? That is unless there is some sort of interference getting into the line on the same 549mhz carrier frequency.

But could a bad modem affect one channel?

If I can be sure its not my modem/wiring that would be great.
I do know there are environmental factors outside of my control.



Wow, I read this article and its symptoms are almost exact.

now to get cable guys to troubleshoot it.

Caps stifle innovation
Gautier, MS
reply to HiyaWiya

Interesting problem.

Call tech. support and tell them that the problem is intermittent. If you're persistent enough they may escalate the issue to the network engineers or send out a tech first. They may be able to place a monitor on the line or something to watch for errors on that channel.

Then again it could very well be an issue with your cabling. What are your modem stats? (SNR, downstream/upstream power, etc) Post SNR for each and every channel if you can.
CableOne 50/2


reply to HiyaWiya

Hello, thanks for the reply.

The snr for all 4 downstream were about high 37 last night at 10pm

Checked now at 11am and they are all at low 36

The event logs show the issue happened again at 4am
The "rcs partial service" error message repeats during this event.
Downstream 1 2 4 have 0 uncorrectable
Downstream 3 has over 11,000,000 uncorrectable

every thing is normal now, speed test shows 49 down 2.12 up, no delays with Netflix.

I reset the counters and none are incrementing at this time.
It's strange how ds3 is good most of the time then starts with this issue.


reply to HiyaWiya

Forgot the power stats

All four channels last night 10pm floating between -0.5 and +0.05
Today at 11am all four are between -1.9 and -1.6

Downstream 3 stats are always in same range as the others however one time during the issue it's snr went down to 32.

Would be funny to find out that this is happening from some guys ham radio lol.

Reading old posts here it seems like when others have connections issues it's more constant.

A tech is supposed to be out soon.
But I hope more is looked at than just dropping in a new modem, there is a comment in that volpe article that says only 1 percent of modems were bad.

As for my lines, I checked, even put new connectors on all the rg6 the only older connectors left are in cableone outside box, I even remembered to pull the wall plate and replace that connector behind it along with the wall plate


reply to HiyaWiya

I suffered the same problems with an Arris TG862 for about a year under the $75 per month "Triple Play" deal a few years ago. It was totally intermittent... some weeks it would purr along just fine and other weeks the slowness and packet loss would make internet and phone virtually worthless. I eventually requested a replacement TG862 that acted exactly the same. I was at a total loss how to proceed along with Cableone tech support.

Eventually I talked Cableone out of the "Triple Play" contract without penalty and kept cable / internet while dropping phone. I bought my own Motorola Docsis 3.0 wireless gateway. My net speeds have been 50+ mbps constantly since day 1 of installing the Motorola with absolutely no interruptions. The difference is like night and day.

Arris does not have the best reputation in the modem industry and MANY folks report issues with them.



The modem just may be too sensitive to noise.

The tech found no issues when he was here.
Lines are good and the modem was running perfect.
Of course it had the issue 5 hours later

The Arris handles a wide range of frequencies- cable modulation, telephone conversion, wifi.
So its having to deal with frequency range in the low KHz to high GHz and because FCC requires these devices to accept interference and not cause interference, this wide range means the modem is going to very sensitive to any noise.

So you really end up needing near perfect wiring to cover your responsibilities.

In the end I have new connectors, fully soldered splitters (for shielding), verified grounding, terminated jacks.

The issue still happens.

Note that if you are having similar issues and have verified all your side, then you are good, theres not much else you can do than going with another modem like cableonehs suggested that may be less sensitive.

All it takes is noise from outside your house to cause this issue.
For example, many new video cards operate at the same frequencies as the cable modem, so if a neighbor has a PC with that type of video card and has a TV tuner in the same PC, its very possible for their video card to bleed a signal into the cable system and cause the problem.

I have even read where after a Uverse conversion the cable company did not disconnect their side of the tap, so the uverse tuner was broadcasting down the node.

The only real solution is for the cable company to be proactive
and since their side is already logging the connections, cross reference the locations of the bad signals and audit that node.