Welcome to the Community!

If you are looking for something specific, please use the search bar to check if someone else has asked or answered the same question before posting a new question. Check out our Community Instructions for other FAQ's.

RE: Constant T3/T4 Timeouts + Possibly fixed on my own.

AndrewLBAndrewLB Posts: 10 ✭✭✭
edited September 2020 in Connectivity Sep 07, 2020

Ok.... so a couple days ago my Spectrum (formerly TWC, Former Adelphia, and anciently former Comcast) internet started losing connection. My modem is an Arris SB6183 so i gave support a call and was told my modem signal levels were fine after doing the standard modem reboot and was told it's likely an issue on my end and they'll send out someone on Sep 11th (i called on the 4th). Not content with broken internet for who knows how long, and being fairly adept at DIY, decided to check out the modems signals and from my experience.... the signal levels, primarily the uplink was anything but normal.

Those upstream power numbers are definitely too high. So i walked around the house and checked the ground wire that runs from a 3 way splitter near the roof to a garden hose tap at ground level. All was well there. Everything else looked ok except for a section of Coax from the mid 1980's to my downstairs TV that apparently the Time Warner tech didn't replace when they did an (almost) full rewire about 5 years ago. It's probably 30ft and absolute garbage. There was also a splitter in my bedroom which branched off to the cable modem and used to also go to a TV, but due to price hikes, i got rid of that DVR a year ago. I didn't have any Coax 75hz terminator caps, I just yanked the splitter and relocated the modem/router temporarily under the desk since there wasn't enough slack.

Here are the results....

So far i haven't had any T3/T4 timeouts and its been about 3 hours now. Correct me if i'm wrong, but aren't these power levels at the upper end of what is acceptable? I'm thinking that once I either have Spectrum (or i may just do it myself) replace that 35' section of antique coaxial cable from the mix, those upstream power levels should come down a bit more, and i may see some improvement on the signal/noise ratio? I saw in another thread some people recommend using a 6db atten in front of the cable modem which makes sounded logical.

So from what I gathered from this is due to the multiple splits in the cable line, downstream signal strength decreases with each connected device and having a splitter hooked to a single device with the other connection not terminated does the same. This low signal then causes the modem to crank up its output power, which then goes beyond the acceptable range, causing the timeouts? That sound right?



  • RAIST5150RAIST5150 Posts: 832 ✭✭✭✭
    Sep 07, 2020

    45/46 is kind of a :"normal" range in many markets. And yes... 51 is bad--geting into automatic reboot territory at that point.

    Don't pad your line. If you get the wrong type, you will cause the modem to raise upstream levels again., and your downstream levels are hitting right in a sweet spot that Spectrum likes to see.

    Upstream power starts low on reboot, and if the headend is having trouble getting signal from you, the modem will start raising upstream power in an effort to clean it up. So padding the line or running longer cable runs (or a lower quality cable) risks causing that value to go up.

    But yes, get those lines cleaned up. Any unterminated port/line in your run risks more noise and such. Want to reduce things to as few splits as needed to get the job done so there are no open lines and less noise/loss injected along the way, and as short a run as is practical to your modem..

  • AndrewLBAndrewLB Posts: 10 ✭✭✭
    Sep 08, 2020

    Well this sucks. Internet went down again today. Those upstream levels crept up since i removed that splitter. Here are the numbers right now....

    Any suggestions? The splitter I had removed isn't one of those CommScope ones i see most people post pictures of. Its an older Time Warner SV-2GT 5-1002mhz. There is another one of these still hooked up in the another bedroom which goes to a standard TV mini box to get normal TV, and the phone modem. It's not grounded. The only grounded splitter is the one outside up on the fascia two floors up just below the roof shingles on the side of the house and that one is a 3-way.

    Since Spectrum is sending someone over on the 11th ill just tread water since its not rebooting constantly like it was the other day.

    Random thought.... i haven't had spectrum come out to do anything since they bought out TWC. I'm not gonna get charged for them coming out right? For what they charge every month for this service, it had better be on the house..

  • AndrewLBAndrewLB Posts: 10 ✭✭✭
    Sep 08, 2020

    I was just thinking that all of this started the day this horrible heatwave hit Southern California. Could that be to blame?

  • Lake802Lake802 Posts: 92 ✭✭✭✭
    Sep 08, 2020

    Andrew -sorry to hear you are having issues with those recurring T3/T4 timeouts. Your thinking is correct - simplify you coax infrastructure, getting rid of old unnecessary splitters, replacing old coax etc.

    In some cases you can assess the impact your internal wiring and splitters are having by plugging the modem in at the demarc and observing the signals from there. Comparing the signals at the demarc potentially bypasses your current home wiring so you can then better more factually determine if it is worthwhile to do a new run of coax from the demarc to your modems location inside the house.

    A recap of the signal levels for your modem are available on the arris website. I listed them below for reference.

    In some cases it may be necessary for an onsite tech to replace the segment of coax that goes from the demarc down to the connection at the street. The technician can usually assess whether that is necessary or not. You are entirely correct that temperature and humidity extremes can impact coax connections .

    Since the goal is reliability of signal reaching your house, would also encourage you to let Spectrum help you by replacing that Arris6183 with Spectrum model appropriate for your area. There is no additional cost to you for using the Spectrum supplied modem. Once you have reliable signal coming into the house and modem, it makes sense to add whatever your preferred wifi router is improve your overall internet experience.

    When the Spectrum tech does arrive for service call, its helpful to share your findings with them and knowledge of splitter locations or other efforts recently attempted to mitigate signal issues. They will help to ensure that modem signals are in spec (RX/TX/SNR) and there are no T3/T4 or errors of any kind in the modem log after reboot.

  • AndrewLBAndrewLB Posts: 10 ✭✭✭
    Sep 09, 2020

    Why would i get rid of my perfectly good cable modem that is completely appropriate for my area for one of those crappy ones Spectrum offers? It's on the approved modem list and was even recommended by Spectrum when i needed to upgrade my previous modem tor the speeds i have now. You can't even check your signal levels anymore.

    Levels have been good all day, zero reboots.

    Before i have a tech come out i'm gonna give a friend a call who does Quality Assurance for Spectrum and see what he has to say about it. Every time i've had a tech come out it's turned into a multi visit ordeal and i dont have the time or patience for that.

  • glenveeglenvee Posts: 281 ✭✭✭✭
    Sep 09, 2020

    You do NOT need an attenuator of any kind. The first thing you should do is get that old bad cable section replaced, and check ALL connectors on all lines to make sure they are more than finger tight.

    Are you in Southern California (you mentioned it in a comment)? Extreme heat can affect signal levels, and with all the fires and other activity in the state, service can be affected periodically statewide.

  • Lake802Lake802 Posts: 92 ✭✭✭✭
    Sep 10, 2020

    Thanks for the update Andrew . The focus here is to resolve the problem and improve the signals and reliability of your service. Eliminating variables such as the modem you have and replacing it with a Spectrum supplied model can help you achieve that. Switching back to your preferred modem is basically a non issue once the signals and coax infrastructure are stable and reliable.

    You are fortunate that good folks like RAIST and glenvee also shared insights that support the general consensus of simplify and improve the inhouse coax signal infrastructure . Measure signals at the demarc so you can factually guage if part of the problem is the coax in your house or not.

    Let the coax tech verify signals are in spec and there an no errors of any kind in new modem log.

    You are correct, occasionally it can be a process. Sometimes some of the issues are upstream from your house. The onsite tech can do a referral to the outside maintenance team if upstream issues need to be further addressed.

    In general , the QA folks are not directly involved in tech support, and would likely advise you to engage tech support and ensure your concerns are addressed and issues promptly resolved.

    Please keep us posted on your progress after the onsite tech visit.

  • AndrewLBAndrewLB Posts: 10 ✭✭✭
    Sep 12, 2020

    Spectrum stopped by yesterday and it turned out to be an issue with their hardware in the box out front of my house where their Amplifier/Tap is located. Corroded connectors and the amplifier itself needed adjusting.

  • karlbeckmankarlbeckman Posts: 2,266 ✭✭✭✭
    Sep 13, 2020

    The combination of corrosion issues & lack of amp maintenance will kill the delivered signal quality every time, and there is nothing the user can do to identify those problems or prevent them in the future. It's all on Spectrum to properly maintain their line hardware and overall physical plant.

This discussion has been closed.