Why do I keep losing OFDM Downstream channels on my modem?

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I'm a Regular
Posts: 300

Re: Why do I keep losing OFDM Downstream channels on my modem?

@mahomed,

You said the main line goes into a 2-way splitter, and then from there into an amp, and the CODA is on the amp. Just curious as to what’s on the other port of the splitter? Why isn’t the CODA on the splitter instead of the amp? Not that it would make a difference with the problem you’re having...just curious. Also, I’ve had packet loss issues when I had my CODA on an Antronix amp. After I reconfigured my setup by putting the main line on a 2-way splitter, connecting the CODA on that splitter, and then the amp running off of the 2nd splitter port where then everything else is connected (home phone and TVs), the internet performance was better. Not saying you should reconfigure anything. I was just wondering why your CODA is on the amp if the amp is running off the splitter.
I'm a Reliable Contributor
Posts: 334

Re: Why do I keep losing OFDM Downstream channels on my modem?

@toolcubed

 

Good question and here is the answer Smiley Happy

 

The main line comes to the side of the house into a 2 way splitter. 

 

One run from that splitter goes into the basement into a unity gain amp that connects into an 8300HD and a Netbox3.  This run has some old RG59 cable buried in the walls and higher frequencies tend to get weaker without the unity amp to keep things level.

 

 

The other run is all new RG6 cable that goes into my bedroom and into the Antonix Amp.  From there, it connects 3 devices:  CODA modem, 4K PVR, 8300 HD.

 

If I wanted to feed the CODA unamped, I would have to add another splitter and connect one leg into the CODA modem and the other into the AMP that would then feed the 2 TV boxes.

 

In the current setup, the biggest drop is only 3.5 dB from the splitter on the side of the house.  Adding more splitters would further weaken the signal on the forward/return lines.  I understand your idea of packet losses but I have not had this issue on the Antronix amp so far.  

 

Hope this helps to clear things up.

 

  

Resident Expert
Resident Expert
Posts: 5,833

Re: Why do I keep losing OFDM Downstream channels on my modem?

@mahomed is that splitter located inside or outside of the house?  If it was inside the house, I'd replace that with a three port splitter.  That splitter would have one port with a -3.5 dB drop and two with a -7 dB drop.  I'd use the -3.5 dB port for the modem and run the other ports to the amplifiers.  

 

Just to point out, there are a couple of amps that are in use.  The older version amplifies everything and is known to cause packet loss.  The newer versions have one port that is marked as a VOIP port.  That amp has a built in splitter, with one leg going to the VOIP port and the other leg going to the amplifier and then out to the ports.  That VOIP port is used for VOIP or modem purposes.  From what I've been told, techs will remove the older amps and replace them with a newer version whenever they run into any that are still in use. 

 

So, depending on where that splitter is, and what amp you have in use for the modem, there might be a way to improve the signal levels and get rid of any packet loss that might currently be caused by the amp. 



I'm a Reliable Contributor
Posts: 334

Re: Why do I keep losing OFDM Downstream channels on my modem?

@Datalink

 

The 2 way splitter is located outside of the house in the green rogers box.  The only way to run another leg unamplified would be to drill a larger hole in the brick and then run wires for another run as well as the cable to power the amp.  This is something I am not wanting to do.

 

As for the Antronix amp, the one I have is the one with the VOIP port (MVRA501B) but that port does not seem to work.  I tried disconnecting the modem run and connect it to the VOIP port and it didn't seem to lock on to any signal.  I then disconnected it and plugged it to one of the other ports and it locked on just fine.  Either I plugged it in wrong or the amp is defective.  It was a brand new sealed amp that was installed.

 

Thanks 

 

 

I Plan to Stick Around
Posts: 72

Re: Why do I keep losing OFDM Downstream channels on my modem?

@mahomed

Short of having a Tech visit the home again, You could try disconnecting everything and couple the coax going to Coda with the main coax coming in, taking all else out of the picture and giving yourself a direct line to Coda for troubleshooting purposes. See what the signal levels are.

I'm a Reliable Contributor
Posts: 572

Re: Why do I keep losing OFDM Downstream channels on my modem?

I rebooted the modem twice within the last 2 days to regain OFDM stats and within 24 hours since the reboots, the modem interface shows OFDM stats as NA. 

 

This issue is starting to become more replicable. Over the past 4 days there has been 3 reboots, and 3 cases were the modem OFDM stats appear as NA. Not sure what to do next.

I'm a Reliable Contributor
Posts: 334

Re: Why do I keep losing OFDM Downstream channels on my modem?

@Hucklebury

 

I think the signal levels would be about the same given that the Amp is a unity design and not adding any boost on the line.

I'm a Reliable Contributor
Posts: 334

Re: Why do I keep losing OFDM Downstream channels on my modem?

@RyzenFX

 

Where abouts are you located (City, Major intersection) as perhaps others may be in the same area or feeding off the same node?  I am in Toronto (Meadowvale Road and Hwy 401) area.  

 

The issue we have here is that we need someone from the Maintenance/Network team to see why the drop occurs.  Calling a Rogers tech visit from a first line tech would be pointless in my case as I have good signal.  In my experience, they will tend to screw something up than fix something.  as @Datalink mentioned, the tools they would need are something they don't carry and won't be able to identify this type of issue.  They have enough tools to identify bad signal and fix it but not when things get more complex.

 

Perhaps if @Datalink or someone more technical can look into things at the main distribution port that might be handy.  The Linex of mine is at Muirbank Blvd just 200 ft. east of Lavery Trail.  The number on the box is 10059431.

 

 

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Posts: 572

Re: Why do I keep losing OFDM Downstream channels on my modem?

@mahomed

 

I'm located in Vaughan, and I have good signal as well (that's what my 32 SC-QAM channels are saying), and my area is really clean in terms of noise. I remember having encountering this issue in 2017 when Dave was around and we diagnosed that everyone connected to my node were affected by the same issue (we found that their OFDM stats were appearing as NA). This led to a firmware fix shortly afterwards (b/c we were able to probe logs out of my modem Smiley Very Happy), but this issue we're experiencing now could possibly be something related with the firmware or could be an area issue. Note: before we diagnosed the problem, a senior tech was sent to confirm good signal strength and that my area was unaffected by noise. This basically localizes the problem down to the firmware.

 

I think the best way to check if this is a widespread issue is checking if the neighbors with the CODA-4582 display the same symptoms as our modems have experienced. When we diagnosed the problem, we found the support tool that front line agents use will falsely show the modem connected to an OFDM carrier, but when logging into the modem user interface, we found that the OFDM stats appeared as NA. 

 

Just some food for thought... but it's worth considering doing the above in order to find the source of the problem.

I'm a Reliable Contributor
Posts: 334

Re: Why do I keep losing OFDM Downstream channels on my modem?

@RyzenFX

 

Thanks for the info.  At this point, I am reluctant about getting a tech visit as my TV and Internet seems to work just fine.  In my experience, I find the first line tech do more harm troubleshooting complex situations than just fixing a bad signal.

 

 

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