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JarthMader's avatar
JarthMader
Aspirant
Dec 09, 2018

Random disconnects with CM400 modem

I replaced a 10 year old, burnt out Motorola modem (no connection issues before it died) with a Netgear CM400 back from Best Buy in August 2018. Since then, I've been getting random disconnects. Usua...
Hardware
JarthMader's avatar
JarthMader
Aspirant
Dec 12, 2018

I did some more research over the past couple days and have made some changes. So, I found the other modem diagnostic page that shows power levels, correctable and uncorrectable errors. With my original setup (50 ft coax cable from the wall to the modem) the power levels on the downstream channels were around -12 to -15 dBmV. After switching my setup around to have the modem and router close to the wall outlet (1.5 ft coax cable, 50 ft ethernet cable to my PC) my downstream power levels are now -3 to -6 dBmV. I haven't had any disconnects for the past two days, but my correcable and uncorrectable errors seem really high:

 

Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables UnCorrectables
1 Locked QAM 256 17 879000000 Hz -5.7 dBmV 34.0 dB 278167 41356
2 Locked QAM 256 18 885000000 Hz -5.2 dBmV 34.0 dB 309215 41345
3 Locked QAM 256 19 891000000 Hz -4.8 dBmV 34.0 dB 343051 59906
4 Locked QAM 256 20 897000000 Hz -5.1 dBmV 34.2 dB 368450 86935
5 Locked QAM 256 21 903000000 Hz -5.2 dBmV 34.2 dB 420998 107528
6 Locked QAM 256 22 909000000 Hz -4.4 dBmV 34.3 dB 557411 122665
7 Locked QAM 256 23 915000000 Hz -3.6 dBmV 34.6 dB 483084 155062
8 Locked QAM 256 24 921000000 Hz -3.9 dBmV 34.4 dB 553903 183524

 

I did a little math (last modem reset was about 42 hours ago), and that comes out to an average of 79k correcables per hour and 19k uncorrectables per hour over all 8 channels. If I'm understanding this all correctly, the uncorrectable errors are bringing down my effective bandwidth. Could this be due to bad wiring in the apartment? Previously on the phone Cox claimed the lines they had control of showed great diagnostic results.