Before you run PingPlotter or speed tests, do this!

How's that for a clickbait headline? But this is really about that headline.

When you're experiencing problems with Cox internet service, you need to check and confirm the reliability of the RF network before you do anything else. The RF network is the network that runs on the coaxial cable that comes out of the back of your modem. Problems in the RF network are very common, and if you don't fix those, results from PingPlotter or speed tests aren't valid. Sometimes RF network problems are caused by your equipment or your wiring, but more often these problems are in the Cox network and are outside of your ability to control.

Most modems will let you check signal levels and event logs by going to the IP address 192.168.100.1 in a browser. You need to find out how to do this for your individual modem. You can't skip this step. The RF network is the foundation of everything. Trying to troubleshoot an issue without checking the RF network is like building a house without a foundation.

There is information available on many sites about modem signals and most of it is accurate. If you post cut/paste signals and modem logs people on the forum will often help you understand them. The only bad information I've seen out there are some Arris pages that make people think their upstream power level is too low. There's basically no such thing as upstream power being too low (unless it's zero) so ignore that. Upstream power being too high is definitely a thing and indicates problems in the RF network.

The most important indicator on the downstream signal page is uncorrected codewords. If you see uncorrected codewords continuously increasing, there is a problem in the RF network. That needs to be resolved before you run PingPlotter or speed tests. Most times you will need a Cox tech to fix this. Every now and then you might get a burst of a few thousand uncorrectables overnight when Cox does maintenance. But if any uncorrectable numbers are increasing during the day, you have a problem that PingPlotter and speed tests won't fix.

When you check the logs, look for CM-STATUS messages (minor issues but if you see them happening more and more often, get ready for bigger problems), dynamic range window violations (minor upstream RF issue but usually indicates that worse problems are coming in the future), T3 timeouts (indicating a bad problem on the upstream RF connection), T4 timeouts (indicating a very bad problem with the whole RF connection), and unexpected modem reboots (usually caused by the modem rebooting to try to re-establish a signal on the RF network).

Once you have good downstream and upstream signals, virtually zero uncorrectable codewords, and clean modem logs with no T3/T4 timeouts, only then should you move on to running PingPlotter and speed tests. Otherwise you're just wasting your time on a problem that those tools can't identify.

TL;DR: Don't waste time with PingPlotter and speed tests until your modem signals and modem logs are clean and correct.

24 Replies

scoomas
New Contributor II
4 years ago
Sooooo can I send you my event log? lol
- scoomas
  New Contributor II
  4 years ago
  
  Arris said my upstream power was too low and not too high
  - Dave9
    Contributor III
    4 years ago
    Cox's equipment tells your modem what upstream power to use. If the Cox equipment isn't receiving your modem signal it will tell it to use more power. Basically that info from Arris is just wrong. I think it must have been written by an intern or something. You can put an attenuator on the line to make the numbers look better but the net effect on the line will be the same. If you put a 6 dB attenuator on the line, your modem will put out 43 dBmV, but on the other side of the attenuator, there will only be 37 dBmV going back to Cox. So it has no net effect on the signal you send back to Cox.
Bruce
Honored Contributor III
4 years ago
Actually, the first thing you'd need to do is identify the actual symptom. For example, if you're only experiencing a problem with a specific application, such as a game, you should begin with ping, PingPlotter, tracert, etc. This would quickly indicate a potential problem somewhere remote on the network(s).

However, if you're experiencing a problem with overall connectivity...all your applications share the same router and modem...then you should begin with the signal specs of your equipment.

The problem with signal specs is a lot of subscribers don't know the acceptable ranges of measurement. There are a lot of sites recommending these ranges but only Cox can provide this information...because it's their network. You could argue the specs from another site but it'd be a moot point.

I think Cox wants these ranges of specs to be a secret. If never read a moderator's assessment of an out-of-spec signal. It's always we'll send a tech to your house.
- Dave9
  Contributor III
  4 years ago
  I don't think Cox wants them to be secret as much as they don't see the value in publishing the information to non-technical end users so they don't bother publishing them. I can also see why the moderators don't want to make a diagnosis since they could then be held to that diagnosis which might later turn out to be wrong. That's why we users have to discuss these topics amongst ourselves.
  
  Signal strength is really a secondary indicator anyway. If you downstream signal levels are -14 but you have 0 uncorrectable packets, then it's all good. By the same token, if your downstream signals are +3 and you have 10 million uncorrectables, you still have a big problem. Basically, downstream signals can show you if you might have a giant problem if they're below -15 or above 15. Beyond that, SNR and uncorrectable packets are more important.
  
  Same goes for upstream power. If your upstream signals are "too low" but you have all 4 (or 5) channels bonded with no T3 errors then it's fine. But if your upstream is +56 and you only have 1 channel, that's a definite problem.
  
  I know everyone wants a step by step guide that always provides a definite answer but that doesn't really exist. Unfortunately we have to learn some details of how the cable modem system works in order to troubleshoot our own problems. IMHO, all cable networks are extremely fragile and require constant maintenance, so the last thing any cable provider wants is for end users to be finding problems and asking for repair. But if you want a good reliable cable connection that's what you have to do.
  - Bruce
    Honored Contributor III
    4 years ago
    The values aren't actual measurements but a log-scale representation to, probably, save space. For example, it's easier to notate -5 as opposed to 0.31622776602 dBmV.
    
    Wouldn't it be nice if Cox could compare our values to a truth table based on our equipment and plan? A 3-light traffic signal within the software of the modem comes to mind:
    
    Green = Within Specs
    Yellow = Operational
    Red = Out-of-Specs
    
    More gooderly, a 5-light model:
    
    Green = Ideal
    Pale Green = Within Specs
    Yellow = Operational
    Pale Red = Out-of-Specs
    Red = No Connectivity
    
    Does Cox measure upstream SNR?