hn4647's profile

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4 Messages

Thu, Jan 14, 2021 7:00 AM

Upstream ranging problems

I need some help figuring out if a problem I’m having is Xfinity or my equipment, looking for some help.

 

Last week we had a brief outage in the afternoon. The internet was out and the TV signal froze on the TV. When I tried using the remote, I got an error message that there was trouble connecting to the internet. Within a half hour service came back. However, later I noticed the upstream light on the cable modem (NETGEAR C6250-100NAS) was blinking. It has done that constantly since the outage. The internet has seemed a bit sluggish but I have not noticed any lengthy outages. The event log shows a constant series of these error messages:

Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=3c:37:86:f0:0b:a0;CMTS-MAC=00:01:5c:68:a8:74;CM-QOS=1.1;CM-VER=3.0;

 

16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=3c:37:86:f0:0b:a0;CMTS-MAC=00:01:5c:68:a8:74;CM-QOS=1.1;CM-VER=3.0;

 

Found some forum posts related to these errors that recommended checking cables. I put on new cable from splitter to modem and when that didn’t work installed new splitter. Same problem. And the modem can take a few to 20 minutes to connect to the gateway. The internet light stays completely off for this time, then finally starts blinking and steadies.

 

When changing the splitter, I powered off the cable box. It took several reboots of the cable box to get the TV signal to come on. I kept getting error messages that there was trouble connecting and to check cables. After three or four tries, it connected. This is the only problem I’ve had with the TV side.

 

I also went to the Xfinity support page that does troubleshooting. It first showed the internet ok but status unavailable for the TV. I refreshed the page several times and the results varied. Sometimes both ok, sometimes internet showed a problem but TV ok, sometimes reversed. When I clicked on modem restart, it said a signal was sent, but the modem never restarted.

 

As I said, even though I don’t have service outages, something is wrong. I spoke with an agent but it didn’t go well. I was on for about 20 minutes but mostly I couldn’t tell what the tech was doing. He kept talking about problems getting connected or the system, maybe trying to restart my modem. I’m not sure he understood my problem. But the call was dropped before anything was resolved and he never called back.

 

Looking for advice on next step.

Responses

EG

Expert

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87.1K Messages

5 m ago

What do the modem's signal stats look like ? Try getting them here http://192.168.100.1 

Please post the *Downstream Power Level*, the *Upstream Power Level*, and the *SNR* (Signal to Noise Ratio) numbers.


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4 Messages

5 m ago

Here is the upstream data as text and a jpg of the full readout.

 

Upstream Bonded Channels (Partial Service)

Channel        Lock Status  US Channel Type   Channel ID   Symbol Rate            Frequency     Power

1          Locked           ATDMA        1          5120 Ksym/sec        36500000 Hz           54 dBmV

2          Not Locked   Unknown      2          0 Ksym/sec   30100000 Hz           0.0 dBmV

3          Not Locked   Unknown      3          0 Ksym/sec   23700000 Hz           0.0 dBmV

4          Not Locked   Unknown      4          0 Ksym/sec   17300000 Hz           0.0 dBmV

hn4647_1-1610640255475.png

 

EG

Expert

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87.1K Messages

5 m ago

The upstream power is too high / out of spec. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In a self troubleshooting effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage types like GE, RadioShack, RCA, Philips, Leviton, Magnavox, and Rocketfish from big box stores like Home Depot, Lowes, Target, Wal-Mart etc. Splitters should be swapped with known to be good / new ones to test

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two way splitter connected directly off of the drop from the street/pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed, and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.

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4 Messages

5 m ago

Thanks. There is only one splitter, brand new RCA, as far as I know. We only moved here two years ago. The main line comes in at a back corner of the house. I guess I'll have to check there because there are some outside cameras (no longer is use) that may split off. Then one cable comes into the house in the opposite corner where I installed the splitter to go to TV box and modem. Assuming the new splitter is ok, the fact that the modem and TV box both seem to impaired, it sounds to me like the problem is upstream of the splitter. Given the sudden appearance of the problem right after an outage, I of course suspect it is somewhere upstream of my house. Frankly I do't relish dealing with the cabling myself, but we'll see. At least it's working somewhat.

EG

Expert

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87.1K Messages

5 m ago

Then, as stated, perhaps you should get a tech out to investigate the problem.

 

Bear in mind that if the premises facing techs can not find or fix a problem at your home, it is they who are responsible for escalating it to their line / network / maintenance dept. techs. The problem may lie beyond your home in the local neighborhood infrastructure somewhere but it is their S.O.P. to start at the home.
Good luck !

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