As far as I know, there aren't any settings to cache files locally, or to use large buffers. You're experiencing a network problem, so you should target a network based fix.
You could use ethernet to wire the Macbook Pro and the QNAP to your network. That would almost certainly speed everything up. Powerline networking is convenient when it's hard to run cables from place to place. Some powerline networking is pretty fast.
You could try installing Wifi range extenders at one or both ends, depending upon which part has a slow wifi connection. Or you might be able to adjust positioning of antennas, or maybe change channels to improve reception.
Good luck!
Brian.
