PI4 buffering

I think a hardware issue here is unlikely. I would do a quick gut check and put that file on a thumb drive and play it locally. Assuming that plays fine then make a system mount using [these instructions] then try playback from there using the file manager. If that is working correctly you can then use path substitution to redirect your paths to this system mount using [these instructions].

Alternatively, if using SMB is an option for your file server you could try adding a SMB source path and try playback using that. If that works you can just use a path substitution to redirect your NFS paths to SMB.

Just be aware in either case it is important that your sources remain the same as they were which hopefully corresponds exactly with any other devices that are sharing that MySQL database. You don’t want to scrape any sources with alternative paths as that will cause problems with your other clients. The path substation will allow paths to continue to be stored in the database using the nfs paths but be redirected on the fly to alternate paths.

The only other thing I could think of is playing around with your file server to change which version of nfs it is using.