Thanks for the answer, Helen Our network guy said me " blocked UDP return packets. The filter is not a statefull firewall, so UDP return ports have to be opened." I do not understand exactly what does it mean but BitTorrent Sync doesn't work ... I checked ip addresses from http://config.usyncapp.com/sync.conf with nmap: I see opened 80 port there but not 3000. Predefined hosts in the client setup didn't help also (I used hostname of my home server and the port number from btsync setup). Do you have any ideas?
