can't update 12.5.30 Update #28

Hi,this is my
System Overview:

• OS: ‪Ubuntu 14.04.3 LTS‬
• Plesk version: 12.5.30 Update #27 , last updated at Mar 29, 2016 06:29 AM

and now I can't update from #28. it show this : The connection has timed out.

I also find someone to help me to deal ,but fail ,I think here is the help but I failed

https://kb.plesk.com/9283

...

can't update 12.5.30 Update #28