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MoCA 2.5 Packet Loss (GameStream/Moonlight Stuttering)

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Druaga

Occasional Visitor
I have a gaming PC in my bonus room, and I use GameStream/Moonlight to stream games to an NVIDIA Shield Pro in my living room. My network consists of three TP-Link Deco X60 mesh routers with three GoCoax WF-803M MoCA 2.5 adapters (see attached network diagram.)

I stream at 1080P 60FPS and it usually works great, but there are quirks that are most noticeable in side-scrolling 2D games. Running the original Super Mario Bros. in an NES emulator, Mario "teleports" for a split second once every 15-20 seconds. I use Moonlight's "Prefer Smoothest Video" mode, and the teleporting happens regardless of what bitrate I stream at (0.5Mbps, 50Mbps, or 150Mbps.)

At first I assumed this happened because MoCA adds 3-4ms of latency, but I'm wondering whether it's related to packet loss. I got the attached results from an iPerf3 server on the Shield and a client on the gaming PC. Throughput is >900Mbps when I run 10 parallel streams, but the UDP tests show packet loss. Also, my GoCoax status screen (see attached) shows "Rx Bad" packets.

If I move the Shield to my bonus room, I connect it to the same unmanaged gigabit switch as the gaming PC. Presumably it never touches the MoCA network. This eliminates the packet loss completely, and it prevents the teleport glitch in SMB.

I've tried quite a few things to improve MoCA performance, including:
  • Replaced an older amplifier with a MoCA-compliant Holland splitter
  • Put 75ohm terminators on every unused coax connector
  • Added Antronix MoCA filters to my point of entry, modem, and STB
  • Replaced old barrel connectors with Holland 3GHz barrel connectors
  • Replaced all coax patch cables with new RG6
Short of replacing the in-wall coax (at that point, I should just install CAT6), is there anything you'd suggest looking at to avoid the packet loss, or is this inherent to MoCA?
 

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You will have to isolate elements in the coax plant as much as possible to figure out where the issue is.

run your test without the Holland splitter. ie point to point between the two locations of interest. You can either use a RG6 barrel connector (union) to connect the two coax or get another GOCoax modem and run two pairs with an ethernet cable between them.

to try to track down which segment of cable might have an issue with packet drops, you will have to pair up two GoCoax and run the test over just one segment of cable. Of course that doesn't tell you if it is the coax or the terminations. Most likely it is a termination or possibly a slightly loose connector on the wall plate. You may be able to pull the wall plate and connect the GoCoax modem directly to the cable in the wall on the cable segment that shows packet errors.

i suppose it could also be an issue with one of the modems as well. Gaming will definitely stress a system. You could get a 25 ft or whatever length you need of pre-terminated RG6 and test the modems alone to see if it is in that part or the in wall coax plant.
i don't know what the 1-2 msec lag will do to your gaming, but i would be surprised if it caused packet loss.
 
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Thanks for the suggestions! I'll try to isolate it this weekend.

Last night, I ran some tests with PingPlotter and noticed that packet loss only occurred with data sent between the Bonus Room and Living Room:

To Study
To Bonus Room
To Living Room
From Study
---​
Good​
Good​
From Bonus Room
Good​
---​
Packet Loss​
From Living Room
Good​
Packet Loss​
---​
Since all the coax segments go to the Holland splitter, I would expect that if a segment or router were bad, this would affect all traffic involving that room. For example, if the Bonus Room was bad, I would expect packet loss with both Bonus Room <-> Study and Bonus Room <-> Living Room. Thoughts?
 
It depends on the total apparent length of cable path between the two modems, if one modem is having a hardware issue, one cable is crimped or nailed, broken sheath, or a sheath wisker is near the core conductor, faulty port on the splitter, total number of connections, etc. in older cable there may be oxidation at the contact between the core conductor and the receptacle. Many times it is a combination of issues that provides the straw to break the camel’s back. Thats why you have to carefully and systematically try to eliminate causes by isolating and testing.

i just noticed you have a three way splitter. Which 3 ports are you using ?
Moca modems have about 40dB of power budget if i remember correctly. Usually, that is more than enough. If the packet loss goes away when you eliminate the splitter, see if you can call up a diagnostic screen with the output power usage on the modem with and without the splitter. There was a reason the previous installation had an amplified splitter.
 
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Here's a photo of the splitter:
  • In Port = Coax from Study
  • Out #1 = Coax from Bonus
  • Out #2 = Coax from Living Room
  • Out #3 = Terminator
Do you see any issues with this part of the setup?
 

Attachments

  • Splitter.jpg
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It might be a bad splitter.

When I join the Bonus and Living Room segments using a barrel connector, I don't see any Rx Bad packets in their GoCoax admin pages. If I connect those two segments to the Holland splitter (and remove the Study segment from the splitter), I start to see Rx Bad packets again.
 
see if the bad packets are associate with specific connections on the splitter or specific cables. Take the two cables of concern, keep one at a constant port on the splitter and move the other one to different ports. Disconnect power to both modems and then connect power. Then repeat except using the other cable.
Make sure you can replicate the issue. One test would be to hook up the other room cable that has not shown an issue to the "bad port" and see if packet errors are reported.
Sometimes it is just how well the connection is made between the cable termination and the receptacle rather than the splitter itself. It can also be an issue with the termination of the cable end.
If the issue is only with one pair of ports or a single port, then replace the splitter. If the issue is with all ports, then there is likely too much signal loss for that path and you will need to get a 0 loss MOCA2 powered splitter or a minimally amplified MOCA2 splitter. When you removed the splitter, you removed about 10 dB of signal loss in the path based on the Holland spec sheet for insertion loss at MOCA frequencies. The barrel connection should be between 3.5 and 5 dB at MOCA frequencies.

IS there any report of the power budget used/avail on the modem diagnostic pages ?
You may have to go to each node, if one modem does not report both modem's values.

Your cable lengths in a house should be short enough that power budget is not an issue unless one of the modems has an issue or the power adapter has an issue. You can try swapping out each of the wall wart power supplies to see if it makes a difference.

Whatever you do, make one change at a time and write down the results.
 
I just tried every possible configuration of the Bonus and Living Room segments in each of the splitter's ports, and I experienced bad packets each time.

An hour before I saw your reply, I ordered the Antronix MMC1002H-B, which has 5-6 dB insertion loss at MoCA frequencies (datasheet). Powered and/or amplified MoCA splitters seem hard to come by --- do you have any recommendations?

I don't see any power reports in the GoCoax diagnostics. Should I be looking at my cable modem's diagnostics pages? It has a page with power levels for downstream and upstream channels.

I'll try swapping the MoCA modems and/or power supplies if I get bad packets with the new splitter.
 
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No, you need something from GOCoax device. contact GoCoax support. There used to be a user here from GoCoax.
 
This is the splitter I use to manage power loss and packet loss. It may be overkill for you
https://www.amazon.com/gp/product/B07CQTHL33/?tag=snbforums-20
I had looked at that in the past. Wouldn't it cause more signal loss than my Holland splitter? The insertion loss looks higher at MoCA frequencies.

Amphenol (IPGH3M4-VF): https://www.amphenolbroadband.com/wp-content/uploads/2019/03/ABS_1002MHz-PS-IPGH3M4-VF-07F17-05.pdf
Holland (GHS-3BPRO-M): https://cdn-docs.av-iq.com/dataSheet/GHS.pdf
 
If you cap the IN port and connect all three cables to the OUT ports, what do you get for your result table above ?
 
If you cap the IN port and connect all three cables to the OUT ports, what do you get for your result table above ?

See below:

To Study
To Bonus Room
To Living Room
From Study
---​
Packet Loss​
Packet Loss​
From Bonus Room
Packet Loss​
---​
Packet Loss​
From Living Room
Packet Loss​
Packet Loss​
---​
 
clearly there is too much loss or noise between the two modems on each path when going through the splitter. That has been consistent from the first test.
If the replacement splitter doesn't change the above result, then something else is going on with the rest of the cabling or the modems are not able to amplify the moca signal enough, i think.

It may be that there is too much noise on the cabling and the signal/noise ratio drops giving the packet errors when the splitter is installed.

Does the sync light on the modem ever blink during one of the above tests ?

contacting GoCoax to figure out how to get to the moca amp power level and line noise indication or just having them replace the modems could be useful. Clearly they work as proved by the barrel connector test. The question is are they operating within spec.

Is the cable RG59 or RG6 in the wall ? it should be stamped or printed on the cable jacket every few feet. RG59 might explain the issue. Wherever the cable from the outside comes into the house and all of the other house cables terminate, you should have enough cable to find the marking on one of the the inside the house cables ( not the one from the cable co).

Do all the cables come back to one point in the house ?
Or are they multidrop at points in the wall ? You can pull a wall plate to show the connection.

If either, what does that look like ?

Actiontec also makes MOCA2.5 modems now.

You could try a pair.

An easy, but expensive, solution would be to get 3 more modems and a 5 port Gbit switch and use that in place of the splitter.
 
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Does the sync light on the modem ever blink during one of the above tests ?
The GoCoax modems have three LEDs. During normal activity, the Power LED stays solid, while the LAN and MoCA LEDs blink quickly (normal if there's traffic passing through.)

contacting GoCoax to figure out how to get to the moca amp power level and line noise indication or just having them replace the modems could be useful. Clearly they work as proved by the barrel connector test. The question is are they operating within spec.
I contacted GoCoax about diagnostics, so hopefully I'll get more info!

Is the cable RG59 or RG6 in the wall ? it should be stamped or printed on the cable jacket every few feet. RG59 might explain the issue. Wherever the cable from the outside comes into the house and all of the other house cables terminate, you should have enough cable to find the marking on one of the the inside the house cables ( not the one from the cable co).

Do all the cables come back to one point in the house ?
Or are they multidrop at points in the wall ? You can pull a wall plate to show the connection.
My cables all come back to the same point in the basement, near where the outside line comes in. The inside cables are marked "E83032 F5967BVV", which I assume means RG59.

An easy, but expensive, solution would be to get 3 more modems and a 5 port Gbit switch and use that in place of the splitter.
The idea is to avoid the insertion loss inherent to splitters?

In any event, I also ordered the Amphenol hybrid splitter. I'll try that and the Antronix this weekend.
 
try this just for fun. Get two pieces of coax , connect them to two output ports, terminate the other ports, connect a moca modem to each and verify good sync, connect a PC to each ethernet port and run the test. you can also run the test with the two modems connected directly.
 
Progress! Disabling every band except "D-High" (previously all three bands were enabled) fixes the bad packet issue:
Band Settings.png

No Bad Packets.png

Unfortunately, this reduces my PHY rates to 2100 Mbps. With all three bands enabled, they're closer to 3500.

Can I avoid the bad packets with all three bands enabled, possibly by enabling the MoCA adapters' built-in network security?

I suspected that my Comcast STB caused a conflict at lower frequencies (even though a MoCA filter is installed on the COAX IN port of the STB.) I tested this theory by re-enabling every band on my GoCoax and unplugging my STB, but the bad packets came back.
 
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The way the coax map was drawn indicated separate cables for MOCA service and cable tv boxes. It that not correct ?
Please redraw the coax map showing actual physical connection if the two are not completely independent.
 

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