Ryzen 5 2600x server. Transcodes are always throttled because everything is always caught up.
50mb upload, but never go above 15 with multiple users. Server is hardwired into a switch that is hardwired into a Google WiFi hub that is hardwired into the modem. All Cat 6 gigabit.
Local play only gives me problems with subtitles. No issues playing anything.
Remote users have issues. Most transcode and many hit buffering issues. No clear reason why. They have good enough download speeds. This happens sometimes with one user, but also it happens with multiple. Can’t recreate it always. When they are buffering, I can play on my LTE phone just fine. Sometimes the buffering is so bad users can’t get it to work again.
Have the remote users check the settings on their Plex apps.
On many Plex apps, the default for remote streaming is 4 Mbps / 720p.
Have them change it to Maximum/Unlimited.
That removes the limits on the client side and should let them direct play instead of transcode.
Note that may create issues on your end. Without a Plex Pass you cannot set server side bandwidth limits for remote users. Depending on media and number of users, it could be easy to overwhelm a 50 Mbps upload, and streams will continue to buffer.
Note too that remote users are at the mercy of the Internet. There is no quality control. Sometimes the connection just sucks and there’s nothing you can do about it. This is especially true if remote users are on a different ISP. If the traffic passes through a congested peering point it will probably buffer and there is nothing you can do about it.