Hi
I found out that my bond interface (10Gb + 10Gb) on 10.14.3 was source of issue. I've reconfigured it to single 10Gb and issue disappeared.
Everything else but SMB worked just fine on bond, strange...
I do have another problem on the same setup, when deleting my (apx. 4000) test files in Finder.
First it take a considerable amount of time and after some time or like 300-400 items deleted ends up with this error:
The "32K" item is one of folders with many small files in it.
On the other hand, deleting one or few files works fine.
Worth mentioning, deleting all of 4000 files from Terminal works fine as well.