Excellent download / Extremely poor upload

I have FreeNas 10.2 on a HP Microserver, with 2 pcs of 1TB discs on embedded minisas in mirror mode (through FreeNas, not through the embedded RAID). Also I have a 120GB (consumer) SSD configered as a cache. It is probably not my best choice to put the SSD on a regular SATA connection, instead of on the minisas, but I wanted to keep the 2 remaining bays free for a second mirror or a Raid5 with 4 discs.

I am getting nice speeds getting files FROM the NAS to alocal SSD drive in my PC (steady...

Excellent download / Extremely poor upload