Uploading process slowing down

My Cloud OS 3 Personal & Network Attached Storage My Cloud
6

24 hours has passed. After 1Kb/s pain, the copying process back to normal for no reason. Really can not understand what is happening.

Also, after bunch of files has been added, appeared issue -

http://community.wd.com/t5/WD-My-Cloud-3rd-Party-Mobile/WD-General-Network-Error-500-iPhone-App-HELP/td-p/870686