Forum Discussion

SDWolf's avatar
SDWolf
New Contributor
6 years ago

Internet signal strength

I purchased a Arris SB8200 cable modem.  It worked for several months until one of your contractors removed an old phone line box after a new phone modem was installed.  The internet modem status page showed it all of the channels locked, but no upstream data being transmitted.  The Cox repairman that came out said Cox has been having problems with the SB8200 modems randomly failing for no reason. 

I put back in an older SB6182 and the internet works now.  I am able to see that the internet still slows down and occasionally drops.

I contacted Arris tech support and they said that the problem is with the signal strength. I am only getting around 35 dbmv to 38 dbmv upstream.  "I reviewed the screenshots you sent and it seems that your SB8200 is currently able to receive signal from your internet provider, downstream channels are at the specified range, unfortunately upstream channels are not how we expected, according to channel type and frequency upstream power levels must be at a range from 45 dbmv (min) to 51 dbmv (max) to let your modem deliver its potential. This is a common issue our customers have when the ISP do not provide the signal that modem requires, that can be the cause of intermittent connection and slow speed issues."

I have had several issues with service over the years, signal strength related, cable and internet.  All of the coax and splitters in my house house have been replaced, other than the run from the pole to the house.  Each repairman that has come out, refuses to replace it.  How can you resolve this?  Is it a problem with cable between the house and the pole, or is it a problem with your infrastructure further up the line? 

  • SDWolf's avatar
    SDWolf
    New Contributor
    6 years ago

    What is the minimum signal strength or standard that Cox should be providing?

    • KevinM2's avatar
      KevinM2
      Former Moderator
      6 years ago
      Hello, your modems signal levels appear to be within the normal parameters and this includes your Tx and Rx levels. I'm not detecting any ingress (noise) on the modem or any packet loss. Are you hard-wired when experiencing drops in service or are you on WiFi? -Kevin M. Cox Support Forum Moderator
      • SDWolf's avatar
        SDWolf
        New Contributor
        6 years ago

        Everything I can find indicates that an upstream signal level should be between 40-52 dBmV for DOCSIS 3.0, and 45-51 dBmV for DOCSIS 3.1.  I was unable to post a picture of my upstream signal levels, but they were 39.2 dBmV.  What can be done to achieve acceptable signal levels?  Additionally, the modem was only able to bond to 4 upstream channels, not the full eight the modem supports. 

  • EdmUse's avatar
    EdmUse
    New Contributor
    6 years ago

    I am having a very similar issue.  A few months ago something happened in my area.  After a lot of tech support, I decided to upgrade my model from an SB6182 to an SB8200, hoping the additional available channels would help.  I also hoped to get gigablast.  At first, it stayed up for several weeks.  The past few months, it's been sporadic at best.  During troubleshooting, we rolled back to my SB6182 and that worked for a few weeks.  Support said my SB8200 was bad, but they keep issuing outage notification for my area.  Additionally, a month ago, I had a rep come out and check my house.  The ONLY line in it is less than 2 years old.  The rep said the signal at my tap was bad, and measured the same (bad) signal at my house.  I found out later than an upstream amp had been messed up.

    I'm taking screenshots of the signal meter every so often.  it's really getting frustrating; I've burned several hours on the phone with support that can't seem to help.  They ether don't know what is going on or don't have the tools to help :(

    I'm back on the SB6182 for the moment.  Going to review the snapshots I took of signal and compare to the notes posted below.

    • KevinM2's avatar
      KevinM2
      Former Moderator
      6 years ago
      Hi EdmUse, we recognize that your time is valuable, and we would be grateful for the opportunity to work with you on a resolution. What issues are you experiencing specifically? Are you on a hard-wired connection or wireless connection? Are all devices experiencing this? -Kevin M. Cox Support Forum Moderator
      • EdmUse's avatar
        EdmUse
        New Contributor
        6 years ago

        Everything is hardwired.  (I do have a wireless). I have a fairly strait forward setup; SB8200 (SB6182 right now...), PFSense nat firewall, and a few desktops hardwired.

        When the SB8200 starts having problems, I noticed that my PFSense starts alerting that it's having packet loss to the external gateway.  I lose IPv4 TCP first, but strangely enough, UDP seems to last a few minutes.  (I assume that's what my voip client uses).

        It's difficult to troubleshoot because it stays online for a few days before it goes offline.  Regardless, I do see issues with gateway checks regularly, usually during off hours.

        Last night, I used the link provided above for signal levels and found that a few aren't in spec.  I noticed other providers (comcast, etc) have pushed firmware updates for the SB8200 and am wondering if cox needs to do something to add whatever is needed for that.