NFS has a reputation for being "lighter" which is great for low-bandwidth crap WiFi but SMB is often more resilient with dropouts and other forms of crap WiFi. There's no universal answer as WiFi is inherently a bit crap, and RPi4 WiFi is at the low-expectations end of on-board WiFi implementations so it's best to experiment and see what works best (or least-worst) for you.
If everything works briliant when you run an Ethernet cable you can join me (and the rest of staff) finger-pointing the WiFi connection ![]()