I’m going on a trip tomorrow and I’m downloading locally on my iPad Pro from my NAS, it’s 2 meters away, my router is a Synology RT2600ac and yet, like every time, I have at least half of the files in error, I have to restart the download, file by file, up to a dozen times per file, if not more…
Are you connecting via SMB?
If so, you may want to try changing the SMB protocol from Auto to either 2 or Legacy. It may be trying to use SMB 3 and erroring out with security responses.
I apologize but I don’t have an iPad to walk through it. It’d be where you have saved shares and then the edit for those and I believe it be in the advanced section of the edit screen.
Sorry, had to run out for a while. Yes, set to SMB2 or I’d even suggest going to “Legacy” first that has worked for quite a few people experiencing problems.