On the flip side, I’ve been using FX file explorer for this for years with no issues, but my roommate on the latest iPhone (a year ago) encountered a pretty horrific oversight in the default Files app’s way to handle this (and no option to use third party apps).
Whenever she tried to copy more than 2GB from the network drive to the phone via Files, the phone would completely lock up and freeze (and stop transferring, which I confirmed by looking at read operations on the home server). She had to hard reboot and copy the files over multiple operations instead of just queuing up 50GB of audiobooks once and letting it transfer in the background. It turns out the Files app handles network assets by loading them all into RAM and then writing them to the iPhone’s NAND, and if you try to perform an operation that takes more than the phone’s current available RAM it just does the Apple equivalent of a bluescreen.
I thought RAID1 enabled faster reads too, because both drives have the complete file. Writes don’t get a speed bump ofc, since those are still bottlenecked by the slowest single drive in the array