buffering despite decent interent connection on pi4

[ghost]

Hello,
I am using the plugin on a Pi4 (4GB) hooked up via lan to a stable 50 Mbit/s line. I get repeated buffering in certain episodes or movies while others run fine. Speedtests on the Pi itself show 45-50 Mbit/s when the buffering occurs. Pausing the show does not help, neither does restarting it.
The same show runs smoothly on 2 Android phones, a Laptop and a PC.
I am running libreelec 95.3, but the issues occured on previous versions as well.

Is there any setting I can adjust to prevent this from happening? It pretty much rendered this great plugin unusable in our case.

Thank you,
Beda