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Modem Repeatedly Requires Restart

Frequent Visitor

Modem Repeatedly Requires Restart

A few weeks ago I upgraded my tv and intrnet service. The internet, when it's working, now has speeds well above 400 Mbps. However, I keep losing internet connection (tv is fine) and have to restart the modem to get the internet service back. This happens, on average, every couple of days.

 

I have a Motrola MB 8600, DOCSIS 3.1, modem. Upstream and downstream connection readings, when connected, look okay. Any suggestions?

Expert

Re: Modem Repeatedly Requires Restart

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

Also post the modem's error / event log entries.



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Frequent Visitor

Re: Modem Repeatedly Requires Restart

Modem.jpg

Frequent Visitor

Re: Modem Repeatedly Requires Restart

I tried to post a scrren grab of the power levels. Didn't work.

Frequent Visitor

Re: Modem Repeatedly Requires Restart

I tried resetting the modem to factory defaults and since then there have been no log entries.

Frequent Visitor

Re: Modem Repeatedly Requires Restart

Downstream

1 Locked QAM256 29 663.0 4.8 36.3 159 0
2 Locked QAM256 1 483.0 4.1 37.7 0 0
3 Locked QAM256 2 489.0 4.1 37.6 0 0
4 Locked QAM256 3 495.0 3.9 37.4 0 0
5 Locked QAM256 4 507.0 3.6 37.2 0 0
6 Locked QAM256 5 513.0 3.7 37.0 0 0
7 Locked QAM256 6 519.0 3.6 37.2 2 0
8 Locked QAM256 7 525.0 4.1 37.3 0 0
9 Locked QAM256 8 531.0 4.0 37.2 1 0
10 Locked QAM256 9 543.0 4.0 36.8 2 0
11 Locked QAM256 10 549.0 3.9 36.8 7 0
12 Locked QAM256 11 555.0 3.6 36.6 14 0
13 Locked QAM256 12 561.0 3.9 36.8 18 0
14 Locked QAM256 13 567.0 4.2 36.7 10 0
15 Locked QAM256 14 573.0 4.6 36.9 19 0
16 Locked QAM256 15 579.0 5.0 36.8 20 0
17 Locked QAM256 16 585.0 5.3 36.9 29 0
18 Locked QAM256 17 591.0 5.5 36.9 31 0
19 Locked QAM256 18 597.0 5.2 36.8 27 0
20 Locked QAM256 19 603.0 4.6 36.6 30 0
21 Locked QAM256 20 609.0 3.9 36.2 76 0
22 Locked QAM256 21 615.0 3.9 36.1 132 0
23 Locked QAM256 22 621.0 4.2 36.3 112 0
24 Locked QAM256 23 627.0 4.3 36.2 122 0
25 Locked QAM256 24 633.0 4.3 36.3 114 0
26 Locked QAM256 25 639.0 4.6 36.2 127 0
27 Locked QAM256 26 645.0 4.6 36.3 152 0
28 Locked QAM256 27 651.0 4.8 36.1 177 0
29 Locked QAM256 28 657.0 4.9 36.3 188 0
30 Locked QAM256 30 669.0 4.4 36.1 178 0
31 Locked QAM256 31 675.0 4.3 35.6 158 0
32 Locked OFDM PLC 159 722.0 5.2 13.9 53 0

Upstream

Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV)
1 Locked SC-QAM 3 5120 17.3 62.3

Expert

Re: Modem Repeatedly Requires Restart

The upstream power at 62.3 dB is way out of spec !! That can cause random disconnects, spontaneous re-booting of the modem, and speed and latency problems. And that is why only one upstream channel is being locked on to.

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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Official Employee

Re: Modem Repeatedly Requires Restart

Hello @MarkGW, thanks for reaching out to our Forums! I'm sorry to hear about the connection issue you have been experiencing on your end. I hope the very useful information @EG provided was helpful. Please let us know if you have any other questions, or if you are still experiencing issues after eliminating the splitters being a possible contributing factor. Thank you! 


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Official Employee

Re: Modem Repeatedly Requires Restart

@MarkGW, we never heard back from you, so I wanted to let you know I will be locking this thread. Please be sure to reach back out if you still need assistance with this connection concern, or any future issues or concerns. We're here to help. Thanks and we appreciate you being the best part of Comcast. 


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Frequent Visitor

Re: Modem Repeatedly Requires Restart

The problem still exists. I've been out of town. I'll check the connections this weekend and get back to you here.

Official Employee

Re: Modem Repeatedly Requires Restart

MarkGW, looking forward to hearing back! 


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Frequent Visitor

Re: Modem Repeatedly Requires Restart

I replace a splitter and nowe have these readings. Are they okay?

 

CableModem.jpg

Diamond Problem Solver

Re: Modem Repeatedly Requires Restart

As @EG noted a while back, your upstream power is still too high by about 8-10 dB. As suggested try to remove any extra splitters, if not, you’ll need a tech out to troubleshoot why the upstream is so high

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Expert

Re: Modem Repeatedly Requires Restart

Yep. Still too high / out of spec.


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Official Employee

Re: Modem Repeatedly Requires Restart

Hi @MarkGW,

 

I agree with @EG & @CCAndrew. You will need to have a tech out. I can help get one scheduled if you haven't done so already. Please send me a private message with your first and last name and the day of the week that works best to have someone out. To send a private message click on my name "ComcastChe", then click send a message. 

 

Thanks. 


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Frequent Visitor

Re: Modem Repeatedly Requires Restart

Technician came out today. How are these readings:

 

After.jpg

Expert

Re: Modem Repeatedly Requires Restart

Better / in spec, but not ideal. 45 dB or lower is more desirable. Bottom line. Live with it a while and see if the problem still happens. Good luck with it !



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Official Employee

Re: Modem Repeatedly Requires Restart

Hi @MarkGW

 

I hope all is well. I just wanted to follow up to see how your services have been working since the tech visit? 


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Frequent Visitor

Re: Modem Repeatedly Requires Restart

The numbers definitely improved after the tech was here. However, the next day I had to restart my modem twice. Since then things have been okay.
Official Employee

Re: Modem Repeatedly Requires Restart

Ok, thanks for letting me know. I'm happy things appear to be ok. If you should happen to have any more issues in the future, feel free to contact us. We'd be more than happy to assist you. Thanks for being a loyal customer. 


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