NAS model?
Previous PMS version?
What is the message?
Is it the “server is not powerful enough…” message?
Hardware accelerated transcoding is currently broken on devices with Celeron J3xxx & J4xxx CPUs. The NAS will fall back to software transcoding, and the Celeron will struggle to transcode video in real time.
If that is the problem you’re having, you can follow progress towards a fix here: 1.32.2.7002.