Infuse buffers when playing high nitrate videos (close to 100Mb/s) although the network is more than fast enough to cache files at a much higher bitrate.
That is on both Apple TV and iPad.
In both cases, the connection speed to the internet is more than 100Mb/s as said by the Speedtest app.
And a 90Mb/s 6 minute video copies in under 2 minutes from my NAS to my iPad using the Files app.
It stops after a while when playing from the NAS in Infuse on my iPad. It start again after some time, but with no sound. If I pause and play the video again, the sound plays again.
As for protocols, I use NFS to access my NAS in Infuse (which used to be the most reliable protocol for that) and SMB in the Files app.
Diagnostic code (iPad) 0NDAX