Rookie

Intermittent internet connectivity at night

Hi, I have met severe intermittent connectivity issue since July. The internet connection will be completely down at around 7-10 pm and it will recover next day at about 7 am. When it is down, the US power will reach 58 dB mv (this is the max power level that my modem can output) and the modem will keep rebooting to try obtaining channels. Today (8/10) afternoon, Spectrum sent some technicians to my home and they found there was a splitter in my neighbor's home and it was hooked on my line. They removed the splitter and told me the issue was fixed permanently.

But later this night, around 8:20, the internet was down again, just like the days before.


I am using an SB6121 modem and it is connected directly to the only coaxial outlet on the wall. I only have internet service from Spectrum, no TV or voice.

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Update on 08/11

It is cloudy outside and the internet is down again. Before the removal of the splitter, the internet will be down when it is raining or cloudy, it seems that the removal does not make any difference.
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Following are the screenshots of the signal page in various situations.

Signal page, when the internet is up before the splitter is removed:


Signal page, when the internet is down before the splitter is removed:



Signal page, when the internet is up after the splitter is removed:

Signal page, when the internet is up and the weather is cloudy after the splitter is removed:

 

Signal page, when the internet is down after the splitter is removed:




I would greatly appreciate any help with this issue since it has lasted so long and it has almost driven me crazy.

Thanks in advance.

DZ

7 REPLIES 7
Expert

Re: Intermittent internet connectivity at night

Upstream is at max, way out of spec and in fallback single ch mode.

 You have a coaxial or corrosion( corroded or too short center wire) or open splitter issue.

 center wire must be shiny copper and extend 1/8" beyond the nuts

Check backside of wall plates, all must be a tad more than finger tight, outside grounding block must be shiny and tight.

 

IF YOU ARE INTERNET ONLY, THERE CAN'T BE ANY SPLITTERS IN LINE, ESPECIALLY WITH AN OPEN PORT.

 

 

 

Rookie

Re: Intermittent internet connectivity at night

Hi MsRaye, thank you for your reply.

I have checked the backside of the outlet and my own coaxial cable, they are tight and shiny. The center wires in the connectors are also long enough. I have called Spectrum and they will send a technician to check the grounding block this Sunday.

Proven Sharer

Re: Intermittent internet connectivity at night

It appears that you have purchased a very old modem and it was not correctly provisioned,  The CMTS server is trying to assign more than four channels for downstream transport.  The channnels are also too widely spaced for that archaic model - the limit for an SB6121 is 36 MHz from lowest to highest.  Spectrum is increasing the internet DS channel count in most locations to 16; major metros and surrounding areas are getting 24 or even 32 DS channels to accomodate even more users.  Therefore you should consider upgrading your older SB6121 modem to a current production device very soon.  My personal favorite is the new Motorola MB7420, a 16 x 4 DOCSIS3.0 device.  Either 8 x 4 or 16 x 4 channel capacity should bring an immediate performance improvement.. 

Rookie

Re: Intermittent internet connectivity at night

Hi, karlbeckman, thank you for your reply.

 

I am living in an old complex near a university, the maximum speed in my area is only 50Mbps and there is no sign of increasing. So I think the network demand is very stable in my area and there is no reason for TWC/Spectrum to upgrade the network. TWC/Spectrum has a monopoly on internet service in my area for quite a long time and this modem worked for me for the past two years until last month. And what is strange is that this modem works in the daytime but not at night. If the outage is due to a high network load, why it recovers at about 7 am? I do not think the network load will be very high from 2 am to 7 am since most people are sleeping at that time.

Expert

Re: Intermittent internet connectivity at night

TWC/spectrum needs to fix the bad upstream path.. +58 dBmv isn't going to work with even a new modem properly...

this is corroded connections or too many or open port splitters or an apartment building issue with wrong/ no bidirectional amplifiers installed.

 REPORT THIS AS UPSTREAM PARTIAL SERVICE, US LEVEL OUT OF SPEC AT +58 dBmv

 

Rookie

Re: Intermittent internet connectivity at night

Thank you for the reply. I will tell the technician about the US issue when he comes to my home.

Highlighted
Expert

Re: Intermittent internet connectivity at night

Hopefully a reset after repairs will get you back into the 36 mHz Downstream acceptance bandwidth. And 4 upstream channels lower than +50 dBmv

 eventually ypu'll need a full bandwidth modem of which most 16 channel ones are capable of since we can't get TWC/spectrum to fix the CMTS allocations properly.