4k uhd stutter or freezing up, audio dropouts

I didn’t say google fstab, I said to search this forum. That would have found lots of ideas, including:

https://discourse.osmc.tv/t/configuring-fstab-based-samba-share-mounts

Before that, I suggest you tried copying the problem file to the Vero (you could use a USB stick to do that) and then try to play it. That would rule out network problems.