Bug in SMB in EX2?

Yup bought the EX2 Ultra diskless with two 10TB gold drives.

Encountered my first perplexing problem that I don’t recall having with single Bay My Clouds.

On my Mac mini running OS X El Capitan 10.11.6 connected to both my 8TB My cloud and my new EX2 Ultra via SMB, the file copying STOPPED after setting in motion a massive file copy from one cloud to another.

We are talking massive directory entry sizes of several million. In just my midi I have 250,000 directory entries and after the file copying process stopped, I tried to delete the whole structure and the deletion process just sat there. No Disk noises, no response on the Mac. Finally killed finder.

So I resorted back to my old tricks by connecting via AFP instead of SMB which handles massive directory sizes much better. Via AFP I was finally able to delete the partially copied Midi directory and restarted the file copy process again, this time only selecting one directory at a time.

Now I can hear the files being copied, where-as previously my EX2 fell asleep.

I am guessing that it might be a Mac problem more than an EX2 problem? or is it just SMB itself?