DOpus copys slowly on smb3 multichannel network drives

It's something we'll be adding support for in the future (via the high-level CopyFile/Ex API, the only thing that can actually take advantage of those features).

At the moment, you could use this as a workaround:

Note that almost nothing will be able to use multichannel mode other than file managers which use that API. Programs that load and save or stream files off the drive will not get the speed increase. It's a very half-baked feature, since the Windows team did not bother implementing it at the right level so that it would work with all file access rather than just one specific and limited API (that's only good for copying a whole file from one place to another, not loading some or all of a file into memory). Using a single faster connection is always best.