FYI, I've already tried the below with zero success:

start PWS with Admin rights start PWS with compatibility settings(with/without admin rights) stop/close antivirus protection(360 total security by Qihu 360 Software Co) & allowed 'sync.exe' in firewall settings(windows 10 OS firewall) already tried accessing this from web browser and is accessible (http://c1-de.sixmirror.com/synq/1ba63c97-2a18-42a7-8380-70886067582e/config.json  as mentioned here https://community.withsix.com/topic/169/error-when-updating-mod/2) clean installS