Netflix video quality too low?

I have registered with Netflix now, but the quality of the films is quite low, although my subscription also supports Ultra HD. In the playback settings, I specified that the best quality should always be used automatically, but nothing has changed. I logged out and back in, but nothing changes. What can help

Poor management?

I immediately thought of it 👍🏼😉

No, the line is very good, besides the automatic adjustment is off. It is noticeable that this is not the case with all films. Some do not run in HD (also automatically), others, even if the good quality should actually be "forced".

Connect via lan if the WLAN does not pack it.