C6300 Frequent short internet drops

I have a C6300 modem/router with Xfiinity cable internet. I have used this exact set-up for several years without any issues, but over the last few weeks my internet has been pretty bad. A...

Swift120
Mar 17, 2022
Just wanted to give an update. I switched to a Motorola MB7621 (24x8 DOCSIS 3.0) modem and another router (an old TP Link that I borrowed) without changing/replacing anything in the coax line. That solved the problem immediately. My guess is the old C6300 modem-router hardware was failing.

Big thanks to FURRYe38 and plemans for helping out!

Swift120

Guide

Mar 09, 2022

ISP has checked signal up to the modem and verified cable and connection quality. There is no splitter installed. Power off for 1 minute and back on didn't make a difference.

Connection page:

<tabindex=-1>Startup Procedure</tabindex=-1>

Procedure	Status	Comment
Acquire Downstream Channel	525000000 Hz	Locked
Connectivity State	Ok	Operational
Boot State	Ok	Operational
Security	Enabled	BPI+
IP Provisioning Mode	Honor MDD	honorMdd(4)

Downstream Bonded Channels

Channel	Lock Status	Modulation	Channel ID	Frequency	Power	SNR	Correctables	UnCorrectables
1	Locked	QAM 256	1	435000000 Hz	-1.9 dBmV	40.3 dB	724335	4590707
2	Locked	QAM 256	2	441000000 Hz	-1.9 dBmV	40.9 dB	0	0
3	Locked	QAM 256	3	447000000 Hz	-1.7 dBmV	40.3 dB	0	0
4	Locked	QAM 256	4	453000000 Hz	-1.5 dBmV	40.9 dB	19	0
5	Locked	QAM 256	5	459000000 Hz	-1.4 dBmV	40.3 dB	304	4471
6	Locked	QAM 256	6	465000000 Hz	-1.5 dBmV	40.3 dB	92016	1199165
7	Locked	QAM 256	7	471000000 Hz	-1.5 dBmV	40.3 dB	0	0
8	Locked	QAM 256	8	477000000 Hz	-1.5 dBmV	40.3 dB	0	0
9	Locked	QAM 256	9	483000000 Hz	-1.5 dBmV	40.9 dB	0	0
10	Locked	QAM 256	10	489000000 Hz	-1.5 dBmV	40.9 dB	0	0
11	Locked	QAM 256	11	495000000 Hz	-1.7 dBmV	40.9 dB	0	0
12	Locked	QAM 256	12	501000000 Hz	-1.7 dBmV	40.9 dB	0	0
13	Locked	QAM 256	13	507000000 Hz	-1.9 dBmV	40.9 dB	0	0
14	Locked	QAM 256	14	513000000 Hz	-2.0 dBmV	40.3 dB	0	0
15	Locked	QAM 256	15	519000000 Hz	-2.2 dBmV	40.9 dB	0	0
16	Locked	QAM 256	16	525000000 Hz	-2.2 dBmV	40.3 dB	0	0

Upstream Bonded Channels

Channel	Lock Status	US Channel Type	Channel ID	Symbol Rate	Frequency	Power
1	Locked	ATDMA	2	5120 Ksym/sec	16400000 Hz	44.3 dBmV
2	Locked	ATDMA	3	5120 Ksym/sec	22800000 Hz	44.3 dBmV
3	Locked	ATDMA	4	5120 Ksym/sec	29200000 Hz	44.3 dBmV
4	Locked	ATDMA	5	5120 Ksym/sec	35600000 Hz	42.8 dBmV

Current System Time: Wed Mar 9 16:46:52 2022

System Up Time: 5 days 06:18:49

FURRYe38

Guru - Experienced User

Mar 09, 2022

A tad bit low on power however with in spec.

Though are you getting some correct and uncorrectables that should be zero on 4, 5 and 6.

Check for loose connections. Make sure all coax jack plugs are screwed in firmly.

Had a factory reset and setup from scratch been performed?

Swift120
Guide
Mar 09, 2022
Yes, verified all connections and factory reset has been performed. Using standard settings now, so no setup after factory reset.
- FURRYe38
  Guru - Experienced User
  Mar 09, 2022
  OK see if this happens again. Possible you might need a new modem...
  - Swift120
    Guide
    Mar 10, 2022
    Still happening unfortunately.
    
    I also had my laptop ping the router to see if it was still reachable during an outage. During the outage there were no sucessful pings. Instead, most pings didn't receive a reponse, and a few resulted in "Destination Host Unreachable". I did not get any "Network is unreachable", which it gives if the wifi is getting disconnected.
    
    My interpretation would be that there is something going wrong in the modem-router, since just bad cable connection (like a bad coax) shouldn't affect the LAN. So time to buy a new modem-router?

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C6300 Frequent short internet drops