"Unexplainable" playback issue affecting a single remote user

General Discussions
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1

Technical details below.

I am posting here as a last resort - I have exhausted every single thing I can think of to resolve this issue, and I can’t even be certain it is related to Plex specifically. But I’m desperate at this point.

Description of the problem:

I host a Plex media server with remote access enabled and working. I recently moved about 20 miles from my previous home, and suddenly one of my most frequent users cannot stream from me anymore. Never had any problems prior to the move. I have 3-4 regular users, plus myself, who can stream remotely perfectly fine as long as I have available upload. Nothing in my setup changed - same ISP, same hardware and wired identically, same state and general area. The hardware was literally powered off, moved, and turned back on. The only noteworthy thing that changed is my public IP range, changing from a 63.x.x.x to a 206.x.x.x.

When this user attempts to stream, the media will load, but after approximately 15-20 seconds it will buffer, and from that point it will buffer continuously after that same interval. It usually recovers after buffering to resume playback, but it will always buffer again after that 15-20 second time period.

When monitoring the dashboard, my remote upload does not even get close to my max upload speed. Remote traffic shows up in intervals, but doesn’t look too far off from when other users stream. It also doesn’t seem to coincide with the buffering itself.

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This buffering occurs with videos of any size, even short 480p TV episodes - though the buffering interval is a few seconds longer.

Playback never fails outright - no errors or “Cannot play media” warnings, and nothing in the logs as far as I can tell, though It’s possible there are other logs I’m not aware of. I have checked both the Plex console and docker logs for the container.

I am less concerned with this and am only including it incase it’s valuable: I have also had similar issues with PlexAmp since moving, where I am only able to stream non-cached music when connected to WiFi, regardless of where I am (local or remote). For whatever reason, when on cell service I can load the library and navigate it normally, but playback buffers forever and never starts. This is with FLAC audio files, so much smaller than video.

WHAT WE HAVE TRIED:

  • Multiple clients - Apple TV, Windows 10 DT app, web browser (FF and Edge) - all configured to stream at ‘Original/Maximum’ to avoid transcoding.
  • Streaming over a VPN
  • Hosting a Tailscale subnet-router as a container on the same Proxmox host, then having the user access the server via IP and stream while connected to the Tailnet. I confirmed that the Tailscale connection is providing access to my subnets.
  • The user is in another state - confirmed that both out-of-state and even out-of-country remote streaming works for other users. One test was from a user typically in the same state as me, so that same account could stream both in and out of state.
  • Changing the port Plex is operating with and adjusting port forwarding accordingly.
  • Adding the user to Plex home.

Notable Plex settings:

  • Video transcoding is OFF.
  • Enable Relay is OFF.
  • Limit Remote Stream Bitrate = No Limit
  • Secure connections = Preferred
  • No plugins are installed

My setup is as follows:

  • Plex Media Server v1.42.1.10060 running in a docker container, inside a Debian VM on top of Proxmox. (Several layers of virtualization, I know, but I have reasons for it. If this was affecting all users, I’d be more inclined to suspect that as the cause.)
  • My router and networking equipment is all Unifi - specific firmware can be provided if useful. Port forwarding is enabled for Plex and points to the VM hosting it.
  • My ISP is GCI, a local provider here in Alaska. They suck, but not sure that would explain this problem. They are also my only option in my area.
  • The remote user is in Oklahoma.

Final Thoughts

I just want to reiterate that this same user could stream perfectly fine prior to my move. They were my most active user by far. I work in IT and have exhausted every troubleshooting angle I can think of, aside from nuking the server and setting up a new one. It makes no sense to me that simply moving 20 miles away would cause this. The only thing I can think of, is that maybe somehow Plex is falling back to the relay somehow for this one user, despite it being disabled? They are the farthest person from me, for whatever that’s worth.

Thank you for reading and any insight. I am happy to supply any other information that may be helpful. I also understand this may not be a Plex issue specifically.

2

Intriguing issue. First thing I’d look at would be the exact method of connection between the two of you. When they next stream from you, certainly do get a screenshot of YOUR dashboard of their connection. We can determine many things about it, but what I’d like to absolutely confirm is the use (or absence) of the Plex Relay. I know you turned it off, but if it turns out to be actually happening, it’d certainly explain a lot of things.

One question, is if the user is using clients (web, apple, Windows) that they have previously seen your server in it’s old location. While the issue happening in all 4 clients at once is unlikely, I’d wonder if it was a cache issue, where each client tries to connect to the server on the old IP. If the client never throws away the old IP, it may try connecting to the old IP (15 seconds) every time it gets packet information, then falls back on the new current IP.

That being said, have you checked your server’s Settings > Network > Custom Server Access URLs setting to see if you happen to have hard-coded your old server’s IP in there?

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Thanks for getting back to me, I really appreciate it!

I added the screenshot of a test stream to the post. You can see they’ve streamed about 1 minute, but the bandwidth graph is about double the time. The buffering is indeed every 15 seconds or so.

Here are the 2 settings you mention - is there somewhere else I can check for whether the relay is still being used? I do tend to agree with you, that it seems like it is using the relay in this case.

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I forgot to add it to the post but I did have the user fully clear cache in both browsers when testing there. I will have them clear the cache for the Windows app and try that too.

-Luke

4

Yeah, none of my theories show up. The peaks in streaming are likely because of how Plex sends video data. While the video itself is 15 mbps, the data is sent in bursts, keeping a few minutes or so of buffered video. You can see peaks of data bursting that look to be about 4x the video itself.

The picture of the client does not show you are using the relay. It would indicate it on the dashboard, so it’s not relaying. I do see a transcode for audio, which shouldn’t ™ cause any issues…

Okay, if it’s not cache (other clients have it too, I think, but i can’t recall how to clear them). The next test is if the account itself is borked. I doubt that is the case, but since your ONE friend has this issue, I’d make them a new test account yourself, invite it to the server, then send the login deets to your friend. See if it works better.

Also, check whether it is the file itself is an issue. Ask them to do something else. I bet you already had checked, but it’s best to confirm.

5

There have been reports about certain ISPs trying to detect, and subsequently throttle Plex streaming traffic.

Your first measure to counter that, should be to change away from the well-known Plex port number 32400 at the WAN side of your router.
Replace it with a random port number between 10000 – 50000. (Or maybe try and use the well-known port number of some other service, like https-proxy or something.)
All you need to do is to edit the port forwarding rule in the router, and change only the “external/WAN” port number. Then tell Plex which number you used, by putting it into the field “Manually specify public port”.

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@Divideby0 This has been ongoing for months and we have tried many different files, sizes, codecs, movies/tv, etc. Definitely not a file issue.

Just had the user try with a fresh account that I made, same problem.

@OttoKerner I have tried changing the port previously, but I’ll try again tonight, maybe with a well known one as you mention. Just to rule it out for sure.

Thank you again for your time.

-Luke

7

Well, we eliminated the most obvious things, so my next guess that I wanted to avoid was “It’s the ISP’s fault!” I hope it’s as easy to prevent ISP interference by doing a port change. Personally, I changed my port simply because I didn’t want to use a port number KNOWN to be opened for streaming traffic, so I picked a different one.

Depending on how the VPN is configured you’d expect that it would prevent interference from ISP activity. But there are all kinds of settings that - if not configured correctly - can leave to leakage.