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The original was posted on /r/selfhosted by /u/hyperparallelism__ on 2025-06-04 17:03:01+00:00.
After a shameful year of troubleshooting I finally figured out why I was unable to stream anything higher than 480p from my home Plex server while traveling abroad.
The Premise
For context, I have a Plex server at home with loads of 4K content that I'd like to be able to access remotely. Everything works perfectly on my home network. Both the server (RTX 3090) and my home network (1 Gbps symmetric) are plenty beefy enough to handle both 4K direct play and even transcodes of 4K content.
I'd consider myself fairly technically savvy so any issues should be trivial to fix... right?
Like any technically savvy user I have a setup that is over-complicated and overkill for my needs:
- Plex is fronted by NGINX.
This is not necessary for Plex, but NGINX fronts all my other home services so might as well.
- Plex/NGINX is accessed over Tailscale.
While abroad, I prefer to access my services over Tailscale (plex.ts.mydomain.com), so I have Tailscale setup on all of my individual devices.
- Plex/NGINX can be accessed via my home IP.
In case Tailscale falls over or has issues, NGINX is port-forwarded and accessible via my home IP directly, allowing me to bypass Tailscale (plex.mydomain.com).
- My home subnet (
172.30.0.0/16) can be accessed over Tailscale.
Since not all devices can run Tailscale, and I may need to do some surgery on my home network while abroad (e.g., to access IPMI/KVM to reboot my servers), I have Tailscale running on my EdgeRouter as well. Tailscale on my EdgeRouter therefore advertises my home subnet routes, just in case.
The Problem
I travel a lot for work and trying to stream anything from home was utter pain. I could barely get the server to play 480p content while away from home.
All the typical guides/fixes available online start from the common issues. But I had long since ruled those out:
- Is your server network fast enough? Yes -- 1 Gbps/1 Gbps
- Is your client network fast enough? Yes -- I tried on 1 Gbps / 1 Gbps clients as well
- Are you using Plex relay? No -- explicitly disabled
- Can you transcode fast enough? Yes -- server handles multiple 4K -> 1080p transcodes just fine locally
- Have you tried direct play? Yes
Now we start to get deeper into the weeds.
- Have you ruled out peering issues? Yes -- iperf reports 250 Mbps between the locations and packet loss is negligible
- Have you ruled out latency? Yes -- I found some posts that suggested this may be the cause and tried some changes to Plex's
mpv settings to increase buffers. This helped, but only a little.
- Have you ruled out Tailscale's DERP routing? Yes -- I have the right ports forwarded at home, and I tried from non-NAT networks on the remote side. Tailscale reports a direct connection between my server and my client.
Up to this point, I had wanted to keep everything over Tailscale, but if it was not meant to be, it was not meant to be. I repeated all my troubleshooting, but this time talking to my NAS directly (plex.mydomain.com). And... still not working? I can clearly see in the browser's request logs that my Plex client is talking to the right domain -- Tailscale is no longer in the mix. And yet I'm still stuck in the realm of 480p.
The Solution (?)
At this point, I'd resolved myself to my situation and have been dealing with it for the last few months. I'd directed my anger at Plex, I'd directed my anger at Tailscale, I'd cursed the gods of networking.
However, in the midst of troubleshooting another network related issue (this time with ChatGPT as my assistant), it directed me to look at my EdgeRouter's logs. By chance, I had a Plex stream playing at the same time. And what do I see? Out of memory warnings and core dumps!
Turns out my EdgeRouter was constantly near its memory limit (not sure why, didn't used to happen before), and any kind of stressful Tailscale traffic was pushing it over the edge (pun not intended). At that point, the EdgeRouter would begin to kill random processes.
I'm sure some networking gurus will wonder why I didn't check these logs in the first place, but I honestly never considered these two could have a problem. When I first set them up, I had explicitly done stress tests on my EdgeRouter+Tailscale setup to confirm they functioned fine together. At that time, my stress tests showed they worked fine with no issues and minimal overhead. I'm still not entirely sure what changed in the meantime, but clearly it wasn't working anymore. Always check your assumptions, people!
The Missing Piece
"But why was this causing my issues? I'd thought ahead! I'd had an escape hatch! I'd tried to access Plex/NGINX directly and not via my Tailscale IP! Surely this couldn't be the problem!"
So I repeated my troubleshooting steps once again, this time carefully scouring the logs for any sign of Tailscale connectivity. Well, it turns out that when Plex thinks it's on your home network, it will ignore any fancy subdomains you've setup and connect to your machine directly. It will use the 123-123-123-123.YouCanWriteAnythingInHere1234567.plex.direct URL that Plex generates for you to talk to your server over HTTPS. And in my desire to make my setup foolproof I'd shared my home subnet over Tailscale, so of course Plex could talk to my home server's IP directly, regardless of what domain I was using to access Plex.
It turns out that during my testing, I'd assumed I'd taken Tailscale out of the equation by not using Tailscale IPs to communicate with my home server, but I'd never actually turned Tailscale off. So the subnet IP was always available for Plex to see, and it would happily choose it. Always check your assumptions, people!
Once Plex started streaming, my poor EdgeRouter would die and/or start killing processes because of the stress of running Tailscale, and the stream would either crawl or be killed and restarted indefinitely.
As soon as I disabled subnet sharing in Tailscale, I could both stream and transcode 4K content remotely with absolutely zero issues. Turns out I was the problem all along.
Maybe my setup is too esoteric (read: too stupid for my own good) to help anyone else, but I'm posting this tale of woe here just in case it helps another poor soul. Good luck.
P.S. I've since re-configured Tailscale so my server is the one sharing the subnet routes. Everything still works fine in that case. The router also shares the subnet routes. Just in case my server is inaccessible but the router still is. But I don't have that share marked as "accepted" in the Tailscale UI, so they don't do anything until I need them.
