Thank you for your suggetsions, I tried changing the listening port but btsync stil crashes when i try to open the webui. To be more specific: I put the address in my browser and it does kind of work on the first try: it either sais "invalid request" or displays the interface partially (as I said earlier). Then, when I try to load the page again, btsync crashes. This is what I found in the log: [20130327 21:49:06] NAT-PMP: Unable to map port with NAT-PMP. [20130327 21:49:19] HTTP: IP 195.22.96.73: GET /gui/ [20130327 21:49:24] HTTP: IP 195.22.96.73: GET /gui/ [20130327 21:49:24] HTTP: IP 19