mv command of local file to a smb share times out

Client is an iMac early 2009 running ElCapitan, 8GB Ram, 1TB SSD.

Server is a Mac Mini Mid 2011 running Yosemite, 2GB Ram, HD 500GB.

From the clients command line I want to move a file (app. 2 MB) from the client to the server.

like: $ mv localfile remotefile

Sometimes it works, but sometimes it says operation timed out.

The same is with other programs e.g. convert like:

convert local-tiff-file remote-jpeg-file

Is there anything one can do?

Thanks for help