Plex doesn't use my full upload speed.

You must have an app issue which, unfortunately, I know nothing about.

Which app(s) are having the problem? Web TV ? Browsers ? devices?

It happens on the current Android app and on the Built in Chromecast functionality of a Sony TV. I’ve had this issue on basically every client I have used which also includes the Samsung TV app. Sometimes it works and it uploads at 15-20 Mbit/s until the buffer is full but it usually just spikes to 20 and then goes down to the video bitrate. Is that Plex limiting the upload bandwidth on purpose and not working correctly? It seems to change from one hour to another which makes me think that it’s my ISP but the bandwidth goes higher on high bitrate videos which is very odd…

Chromecast in the Sony and android app both have Android OS base in common. Same for Samsung.

How/Why it doesn’t run at full speed until the buffer fills is a function of the app . I am not an app guy so can’t help there but can tell you that once the buffer is full, PMS will send only at the rate needed to keep that buffer full.

I’m having this problem … I migrated my server to another, which is more powerfull in every way including network and i can’t see media with more than 5/6k bitrate.
I tried these tools you talked about, and all seems fine.
On iperf3 i get between machines 97.6 Mbits/sec (because my home connection).

This is so annoying x.x Is there anything that i can do to fix it?

I need to see details of the media, clients involved, and even log files, to know what’s happening.

Also, remember, after calculating the combine audio/video bitrate, the value must be multiplied by 1.2 to account for protocol and TCP/IP overhead.