Slow Infuse connection on Mac OS with NAS Synology

I have a Macbok Air M1, Sonoma 14.0 OS and a Synology NAS. I have no problem on Apple TV and iPhone. But on the Macbok, I have to wait a long time before the movie starts. It keeps spinning the rainbow wheel. The movie starts after a minute. But if I want to change the subtitles, the rainbow wheel spins again for a very long time.