CODA-4582 - Open Issues for Investigation

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Resident Expert
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Re: CODA-4582 - Open Issues for Investigation

Thanks @RogersMoin.  I would have requested the same 🙂

 

@unidisk, ok, so, very interesting.  What model of router do you have?  Depending on the router model in question one question is whether or not it can handle max data rates of 950 Mb/s down.  Depending on when you signed up for gig service, you will see either 30 Mb/s up, or 50 Mb/s up.  Rogers has recently reduced the upload rates for new customers.  If you are a new customer and you haven't done this already, I would advise you to run a factory reset on the router and then set the various parameters from scratch.  Don’t use a backup settings file for reload purposes.  We often see customers arrive from other ISPs who experience issues with their router not delivering the expected data rates.  Usually a factory reset for the router solves the issue as it clears out any data that was specific to the previous modem.  In this case, it might only be part of the problem.  

 

Most of the DOCSIS 3.0 signal levels are high, except for a couple of them and some of the signal to noise ratios are slightly low.  The Signal to Noise ratio isn’t exactly a signal to noise ratio in the conventional sense.  It’s actually an error measurement of where the receive signal is, in terms of time and signal level, versus where it should theoretically be.  So, for some reason, the received signal timing isn’t what it should be.

 

The modem isn’t using DOCSIS 3.1, although it should be.  That is seen in the OFDM (DOCSIS 3.1) section.  By now DOCSIS 3.1 should be turned on for all Rogers CMTS equipment.  The fact that your modem isn’t running DOCSIS 3.1 could point to a noise issue with the OFDM channel that DOCSIS 3.1 should be using on your Cable Modem Termination System (CMTS).  All Rogers modems and cable boxes in your immediate neighborhood use one CMTS, so, there is either a problem with your CMTS, or, there is a noise issue on the go.  That will take a call to tech support to report and enquire about. 

The Upstream signal levels aren’t too bad.  Typically with this modem we’re seeing somewhere around 30 to 32 dBmV, so, your signal levels are a little higher.  That might be another indication of noise in the cable system, where the modem output has to be slightly higher in order for the CMTS to receive and decode the incoming data.

 

Ok, so, call tech support.  Advise the CSR that your DOCSIS 3.0 downstream signal levels are high, for the most part but still in spec, and that a good number of the DOCSIS 3.0 signal levels are below 36 dBmV.  Since the modem is using DOCSIS 3.0 at this time, those numbers are important when you’re talking about the modem performance.  Also let the CSR know that the modem isn’t using DOCSIS 3.1.  Ask if that is an issue with the CMTS, as in, is DOCSIS 3.1 not enabled on your CMTS, or, if its possibly due to a noise issue with your cabling.  Ask the CSR to run a signal check on the modem and to check the noise levels on your modem and that of your immediate neighbors.  The question is, is this an issue with just your modem, or is it a problem for your immediate neighbors as well, as you will all be connected to a local tap.  That local tap, depending on whether you have overhead or underground cabling will be located on a nearby utility pole, or in a ground level green pedestal, located close to your home.  It will provide service to 4 to 6 customers (your immediate neighbors) I believe. 

 

That should give you enough info to have an informed conversation with tech support.  That conversation will hopefully start the ball rolling enroute to better modem performance.  You should see ~950 Mb/s max down, ~33 or 58 Mb/s up, depending on when you signed up for gig service. 

 

Hope this helps.

 

Edit:  in the OFDM section of the data, you should see one channel up and running.  Running DOCSIS 3.1, the modem can provide the max 950/960 Mb/s on a speedtest.  The www.speedtest.net Toronto Rogers or Montreal Rogers servers should be used for speedtests for this modem. The Toronto Beanfield and Montreal Fibrenoire servers are good seconday choices for speedtests. 



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Re: CODA-4582 - Open Issues for Investigation

@DatalinkThanks a lot for the detail explanation. 

 

The test was done by connecting a laptop to the port 2 of the cable modem. The router is connected to the port 1. It appears that both router and the laptop get separate IP address (99.228.x.x). This is a bit surprise to me.

 

I signed up for 500MB down/20MB up. So getting 600MB down is over the higher end. The rate control may not be strictly enforced on Rogers end. Behind the router I can get the similar result. I am using MikroTik 750G router. The APs are 4x4 11ac from our own company. Thus pretty I can get close to over 400MB download over with a 2x2 11ac laptop. Check all the details with the AP and the router and I do not see any issue related to Wifi, L2 or L3 IP layers. However I always do the final test using a laptop with the wired connection.

 

I probably will wait until the problem happens again. At the time the down stream is below 1MB while the upstream can stay around 15-20MB. Then I will do another capture of the signal stats. Then I will call the CSR and ask them to run the test. Definitively I will ask them about DOCSIS 3.1 not being enabled.

 

Thanks again!

Resident Expert
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Re: CODA-4582 - Open Issues for Investigation

@unidisk the modems will support two devices when the modem is running in Bridge mode, as in it will supply independent IPV4 and IPV6 addresses to two separate devices.  The modems are actually supposed to supply an unlimited number of IPV6 addresses, but, I've never gone beyond two devices to see if this will work as expected.  Each device will end up with its share of the plan internet data rate.  Ie: the internet plan data rate is spit between all of the devices plugged into the modem, either in Gateway or Bridge mode.  One point to keep in mind, which I remind customers about, connecting directly to the modem when the modem is in Bridge mode exposes the connected device directly to the internet and all of the scanners looking for open ports and access points.  So, the device has to be able to protect itself from that.  I only advise that configuration for very brief periods of time for test purposes, after which its time to retreat behind a firewall.  No doubt there are individuals who run that configuration full time, but, for the average every day user, I don't recommend it, simply due to potential security issues. 

 

When you run into a slow data rate period of time, if you have the time, log into the modem and see if one of the OFDM channels has gone active.  If there are noise issues going on its possible that the modem is trying to run DOCSIS 3.1 and failing rather badly.  Also check to see if the upper DOCSIS 3.0 signal levels or signal to noise ratios have taken a dramatic drop.  At the same time look for a dramatic increase in the upstream signal levels and the possibility that your modem has dropped down to one upstream channel in an attempt to maintain comms with the CMTS.  All of that points to a cable problem or some type of severe cable noise issue.  If this is an intermittent noise issue it will be a major pain to track down the noise source and isolate it from the cable network.

 

When the internet service is at its worst, that's the best time to call tech support so that the CSR can start to track this down.  Don't reset the modem.  Leave it as is so that the CSR can see where the signal levels and signal to noise ratios are at. 



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Re: CODA-4582 - Open Issues for Investigation

@DatalinkPlease keep in mind that every edit you do we all in this thread get an email for every edit.

Microsoft® MVP Windows Insider - Windows Security
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Re: CODA-4582 - Open Issues for Investigation

That's hardly @Datalink 's fault - I'd rather him be thorough than rush through in fear of hitting the "edit" button. 🙂

 

@Datalink - thank you so very much for your detailed and carefully thought out responses. 🙂

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Re: CODA-4582 - Open Issues for Investigation

I called tech support and requested to speak with a level 2 technician but the person said there isn't really a tech 2 technician anymore. She just told told me to exchange the modem again so I did and I'm still experiencing packet loss and unstable pings. Im getting 30-40% PL to my CMTS, it's pretty bad.

 

I messaged @RogersDave 3 weeks ago but he hasn't gotten back to me yet.

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Re: CODA-4582 - Open Issues for Investigation

Apologies for jumping in on this conversation but I have encountered an issue that I hope you are aware of and have a solution for.

 

I have a CODA-4582U modem / router.  I have setup a VPN server on my laptop (with all traffic from the client going through the VPN) so that I can access files, etc. from my home. 

 

When connecting to the VPN server the throughput is so slow from my iPhone / remote computer that I cannot even load CNN.COM which essentially makes the VPN connection useless.  And yes, I do have the VPN Passthrough enabled and I do have the port-forwarding properly configured (i.e. the connection gets established but the throughput is non-existent).

 

Worth also noting is that I know the problem is VPN related because all other connections (i.e TeamViewer, ScreenSharing / VNC) work consistently and quickly.  The other point is that this problem started when I moved from Bell to Rogers. 

 

Would greatly appreciate a solution / workaround as this performance issue is exceptionally disappointing!

 

 

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Re: CODA-4582 - Open Issues for Investigation

https://www.google.ca/amp/s/www.theregister.co.uk/AMP/2018/01/15/router_vendors_update_firmware_to_p...

Anyone know if the coda is susceptible to this bug? It could explain a few things

Mythen
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Re: CODA-4582 - Open Issues for Investigation

@joelcyyz

I don't have answers, just questions.

 

What VPN protocol you are using?  There are so many!

 

Also, I don't quite understand your topology.  Are you saying that your notebook is acting as the VPN gateway for a bunch of nodes (eg. iPhone)?  How are packets routed?  iPhone <-> CODA <-> notebook <-> CODA <-> cloud... ?

 

I assume that your CODA is not in bridge mode (although that would make topology easier to understand and avoid the horrors of NAT).

 

VPN passthrough is often a joke.  What does it mean?  I think it usually applies only to IPSec (but I haven't paid attention to this aspect of the CODA).  At least many implementations I looked at broke IPSec.  Better to use the horrible NAT traversal hacks to IPSec.

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Re: CODA-4582 - Open Issues for Investigation


Hugh, appreciate your input.  Two things:

1. I have responded in-line and in red below; and

2. I am now more convinced than ever that it is a Rogers implementation that is specifically put in place.  Why, because when speaking to Rogers they specifically advised that they do not support end users installing servers (i.e. VPN, web servers, etc.) and therefore limit this capability.  I think this very unfair in that while I understand protecting against the use of high volume servers, how does my little VPN which only 2 or 3 people dial into create a bandwidth threat!

NOT COOL!



@HughR wrote:

@joelcyyz

I don't have answers, just questions.  Well perhaps your questions will lead to answers so here goes!

 

What VPN protocol you are using?  There are so many! L2TP

 

Also, I don't quite understand your topology.  Are you saying that your notebook is acting as the VPN gateway for a bunch of nodes (eg. iPhone)?  Yes, except only for 1 iPhone and 1 to 3 Laptops. I am running VPN server software on my MacBook. How are packets routed?  iPhone <-> CODA <-> notebook <-> CODA <-> cloud... ? Yes, you have it!

 

I assume that your CODA is not in bridge mode (although that would make topology easier to understand and avoid the horrors of NAT). Correct, it is NOT in bridge mode!

 

VPN passthrough is often a joke.  What does it mean?  I think it usually applies only to IPSec (but I haven't paid attention to this aspect of the CODA).  CODA has specific pass-through settings for EACH of IPSec, PPTP and L2TP At least many implementations I looked at broke IPSec.  Better to use the horrible NAT traversal hacks to IPSec.