@miksky,

I would honestly take a look around the other forums, especially those specific to Linux networking. It looks like SMB has some odd behaviors in Linux, and sometimes even WIndows by the looks of it.

A lot of the other forums provide solutions, such as enabling parameters for the error you provided; as far as I can tell, there has been no behavior reported for any Archer Router that is similar to this behavior, so I am inclined to believe that it may be a setting on Linux. 

Have you been able to test the file transfer rate to a different client? If another client has no issues, we can then verify if there is a server setting/incompatability; or if the LinuxOS was the cause.