30Mbps instead of 300Mbps and daily spontaneous router reboots

Question

Hello,

For the past month or so, I'm only getting 10% of the download speed of my plan (300Mbps) and every day around the same time (10:30am or so) my router spontaneously reboots, and takes sometimes upwards of 30 minutes to come back up. Some days it does this 2 or 3 times.

I did a "chat" on the comcast website a few days ago, and the support rep told me I had to contact my modem maker (since I own it) -- which I did, and Arris told me that the power levels are out of spec. Some (but not all) of the downstream channels are lower than -15 dBmV and some of the the upstream channels are lower than 33 dBmV. There are also a lot of "Uncorrectables" for several of the channels.

Yesterday, I check it and and saw that the downstream power levels were all in spec (all around zero!), and my download speed was back where it should be (~250Mbps)! Yay, right? No. 2 hours later, I check again and it's back to 30Mbps and the power levels are below spec again, and then as I'm looking at it, the router spontaneously reboots again.

This is all on a wired gigabit ethernet connection, so slow wifi is not the issue.

Apparently there are signal issues in my neighborhood, even though the comcast website (and the support rep I chatted with) say there are no issues on their end. I've talked to other people in my area who also have the rebooting router issue.

What's the best way to get this escalated so an engineer can look at it?

Thanks in advance,

-Erik

Erik_Stackhouse · Answer

Upstream 1536.50 MHz31.50 dBmVDOCSIS2.0 (ATDMA)5120 kSym/s64QAMUpstream 2817.30 MHz33.00 dBmVDOCSIS2.0 (ATDMA)5120 kSym/s32QAMUpstream 3723.70 MHz33.50 dBmVDOCSIS2.0 (ATDMA)5120 kSym/s64QAMUpstream 4630.10 MHz33.00 dBmVDOCSIS2.0 (ATDMA)5120 kSym/s64QAM

Erik_Stackhouse · Answer

Downstream 133651.00 MHz-13.50 dBmV30.00 dB256QAM130105803112220Downstream 29501.00 MHz------------------------Downstream 310507.00 MHz------------------------Downstream 411513.00 MHz------------------------Downstream 512519.00 MHz-8.00 dBmV30.15 dB256QAM234273950Downstream 613525.00 MHz-4.50 dBmV33.96 dB256QAM74294600Downstream 714531.00 MHz-6.70 dBmV32.68 dB256QAM3400Downstream 815537.00 MHz-12.10 dBmV26.97 dB256QAM19511509606444490959Downstream 916543.00 MHz------------------------Downstream 1017555.00 MHz------------------------Downstream 1118561.00 MHz-13.30 dBmV27.07 dB256QAM341305692273895723Downstream 1219567.00 MHz-13.30 dBmV27.97 dB256QAM341240696717793Downstream 1320573.00 MHz------------------------Downstream 1421579.00 MHz-13.70 dBmV28.33 dB256QAM742712338752523149Downstream 1522585.00 MHz-14.50 dBmV27.61 dB256QAM34146235462329Downstream 1623591.00 MHz------------------------Downstream 1724597.00 MHz------------------------Downstream 1825603.00 MHz------------------------Downstream 1926609.00 MHz------------------------Downstream 2027615.00 MHz------------------------Downstream 2128621.00 MHz------------------------Downstream 2229627.00 MHz-14.90 dBmV28.46 dB256QAM743063292100282Downstream 2330633.00 MHz------------------------Downstream 2431639.00 MHz------------------------Downstream 2532645.00 MHz-15.30 dBmV28.70 dB256QAM345427560Downstream 2634657.00 MHz-13.00 dBmV31.20 dB256QAM3413360Downstream 2735663.00 MHz-15.60 dBmV28.60 dB256QAM34272500775Downstream 2836669.00 MHz------------------------Downstream 2937675.00 MHz------------------------Downstream 3038681.00 MHz------------------------Downstream 3139687.00 MHz-13.60 dBmV31.30 dB256QAM34590Downstream 3240693.00 MHz-15.20 dBmV29.70 dB256QAM34355710

Erik_Stackhouse · Answer

These show up in the log about every 30 minutes:

1/10/2021 12:44	84020200	5	Lost MDD Timeout;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;
1/10/2021 12:44	84000700	5	RCS Partial Service;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;

BruceW · Answer

@Erik_Stackhouse wrote: ... What's the best way to get this escalated so an engineer can look at it? ...

They always begin troubleshooting where the problem is observed, so if you haven't had a premise tech out to look at this, that's where you need to start.

Signal problems like the ones you've posted are often due to poor coax connections or damaged coax cable, usually in or near your home.

If you want to troubleshoot this yourself, please see Internet Troubleshooting Tips.

If you can't fix this, call them or use Chat. Insist they send a tech out to identify the cause and correct it.

If the tech finds bad coax, splitters, amplifiers, or connections in your home (even if Comcast originally supplied them) you'll probably have to pay for the visit unless you have their Service Protection Plan (https://www.xfinity.com/support/articles/service-protection-plan, closed to customers that don't already have it). If the trouble is due to a faulty Comcast rental device or anything outside your home you shouldn't be charged.

Erik_Stackhouse · Answer

Ok, thanks for your reply.

I guess I'll have to use the chat again and ask them to send out a service tech. The only pysical connections are the grounded 1-1 connector block on the outside of the house, then there's a 1-1 connector block, just inside, and a cable goes right from there to the modem. I've already checked the tightness of all three connections, so it's not that, and the modem itself seems fine, since it *does* work like it's supposed to when the signal strength in spec.

BruceW · Answer

@Erik_Stackhouse wrote: ... I guess I'll have to use the chat again and ask them to send out a service tech. ...

I should have said in my previous message: If the premise tech finds out-of-spec signals at the tap or pedestal and cannot correct them, it is up to them to pass the problem up the line to someone who can. Keep leaning on them to get this fixed, and good luck!

Erik_Stackhouse · Answer

Thanks.  I will get to the bottom of it one way or another.  I don't usually *need* the 300mbit download, though it's handy when I do, but the constant reboots are really annoying.

Erik_Stackhouse · Answer

Wow.  Another conicidince.  It rebooted again within minutes of my last post, and when it came back up my event log has errors in it again.  I guess I'll have to have them send a tech out after all, though this could be really frustrating, since the issue is intermittent now.

Erik_Stackhouse · Answer

Interestingly, without doing anything at all, my signal power levels are fine now, and the router hasn't spontaneously rebooted in over 48 hours.  I guess it's just a conincidince that this happened within hours of my post on this forum?

BruceW · Answer

@Erik_Stackhouse wrote: ... now my signals are like 20 times better than they were. ...Sounds good, thank for posting your results, and happy surfing!   😉

Erik_Stackhouse · Answer

Another WOW: I chatted again with customer support, and they sent out a tech, who was here within an hour, and had to replace the line from the pole to the house, which took a little over an hour, and now my signals are like 20 times better than they were.  Couldn't be happier.  Comcast service is really good if you are persistent.

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Erik_Stackhouse

30Mbps instead of 300Mbps and daily spontaneous router reboots

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Upstream 1	5	36.50 MHz	31.50 dBmV	DOCSIS2.0 (ATDMA)	5120 kSym/s	64QAM
Upstream 2	8	17.30 MHz	33.00 dBmV	DOCSIS2.0 (ATDMA)	5120 kSym/s	32QAM
Upstream 3	7	23.70 MHz	33.50 dBmV	DOCSIS2.0 (ATDMA)	5120 kSym/s	64QAM
Upstream 4	6	30.10 MHz	33.00 dBmV	DOCSIS2.0 (ATDMA)	5120 kSym/s	64QAM

Downstream 1	33	651.00 MHz	-13.50 dBmV	30.00 dB	256QAM	130105803	11222	0
Downstream 2	9	501.00 MHz	----	----	----	----	----	----
Downstream 3	10	507.00 MHz	----	----	----	----	----	----
Downstream 4	11	513.00 MHz	----	----	----	----	----	----
Downstream 5	12	519.00 MHz	-8.00 dBmV	30.15 dB	256QAM	234	27395	0
Downstream 6	13	525.00 MHz	-4.50 dBmV	33.96 dB	256QAM	742946	0	0
Downstream 7	14	531.00 MHz	-6.70 dBmV	32.68 dB	256QAM	34	0	0
Downstream 8	15	537.00 MHz	-12.10 dBmV	26.97 dB	256QAM	195	115096064	44490959
Downstream 9	16	543.00 MHz	----	----	----	----	----	----
Downstream 10	17	555.00 MHz	----	----	----	----	----	----
Downstream 11	18	561.00 MHz	-13.30 dBmV	27.07 dB	256QAM	34	130569227	3895723
Downstream 12	19	567.00 MHz	-13.30 dBmV	27.97 dB	256QAM	34	12406967	17793
Downstream 13	20	573.00 MHz	----	----	----	----	----	----
Downstream 14	21	579.00 MHz	-13.70 dBmV	28.33 dB	256QAM	742712	3387525	23149
Downstream 15	22	585.00 MHz	-14.50 dBmV	27.61 dB	256QAM	34	14623546	2329
Downstream 16	23	591.00 MHz	----	----	----	----	----	----
Downstream 17	24	597.00 MHz	----	----	----	----	----	----
Downstream 18	25	603.00 MHz	----	----	----	----	----	----
Downstream 19	26	609.00 MHz	----	----	----	----	----	----
Downstream 20	27	615.00 MHz	----	----	----	----	----	----
Downstream 21	28	621.00 MHz	----	----	----	----	----	----
Downstream 22	29	627.00 MHz	-14.90 dBmV	28.46 dB	256QAM	743063	2921002	82
Downstream 23	30	633.00 MHz	----	----	----	----	----	----
Downstream 24	31	639.00 MHz	----	----	----	----	----	----
Downstream 25	32	645.00 MHz	-15.30 dBmV	28.70 dB	256QAM	34	542756	0
Downstream 26	34	657.00 MHz	-13.00 dBmV	31.20 dB	256QAM	34	1336	0
Downstream 27	35	663.00 MHz	-15.60 dBmV	28.60 dB	256QAM	34	2725007	75
Downstream 28	36	669.00 MHz	----	----	----	----	----	----
Downstream 29	37	675.00 MHz	----	----	----	----	----	----
Downstream 30	38	681.00 MHz	----	----	----	----	----	----
Downstream 31	39	687.00 MHz	-13.60 dBmV	31.30 dB	256QAM	34	59	0
Downstream 32	40	693.00 MHz	-15.20 dBmV	29.70 dB	256QAM	34	35571	0