OK folks - "seasoned network administrator" here. I've been hoping to use BTSync to share some business-related files & directories from my employer's systems, to let their clients more easily access some data, etc. But I've run into an 'Unexpected behavior!' I set up the 'server' - Windows 2008 R2 with BTSync, and share the folder. I've also set a custom 'listen port' and performed a MANUAL NAT / port forward. When the client (who is behind NAT and is *not* supporting uPNP) connects, they get a low, low speed of around 50kilobytes/second, even though the client's download pipe is many, many times that, and the server's upload pipe is many times that as well. When reviewing the open connections on each end, I could see that the 'client' was in fact NOT connecting directly to the 'server.' Is there a reason that the 'relay' servers were being used, even though there was the ability for at least a one-way direct connection? (Yes, I've tested the direct connection, by telnetting to the remote system on the custom port, and I was able to establish a connection). The configuration is fairly normal. Both systems are behind NAT firewalls. The "server" has the custom BTSync port forwarded to it. The expected behavior - direct connection from 'client' to 'server' did not happen. Why? I'm confused. Also, in the logs, I saw the following unexpected entries. Note that port "34780" is *not* the port I used - I in fact specified port 61223 - the 'lan port' it's trying to connect to is the right one, but the port it's trying to connect on the actual WAN interface is very wrong! [2014-02-13 12:59:01.296] ping xxWAN.IPxx.253.205:34780 directly[2014-02-13 12:59:01.296] ping yyLAN.IPyy.63.13:61223 peer local address[2014-02-13 12:59:02.296] Sending broadcast ping for share 5678obfuscatedshare500[2014-02-13 12:59:02.296] Sending broadcast ping for share 0123ObfucsatedShare012300071[2014-02-13 12:59:02.296] Send ping to peer (01234567obfuscatedpeer000C99) for share 0123ObfucsatedShare012300071:[2014-02-13 12:59:02.296] ping xxWAN.IPxx.253.205:34780 directly[2014-02-13 12:59:02.296] ping yyLAN.IPyy.63.13:61223 peer local address[2014-02-13 12:59:03.296] Sending broadcast ping for share 5678obfuscatedshare500[2014-02-13 12:59:03.296] Sending broadcast ping for share 0123ObfucsatedShare012300071[2014-02-13 12:59:03.296] Send ping to peer (01234567obfuscatedpeer000C99) for share 0123ObfucsatedShare012300071:[2014-02-13 12:59:03.296] ping xxWAN.IPxx.253.205:34780 directly[2014-02-13 12:59:03.296] ping yyLAN.IPyy.63.13:61223 peer local address[2014-02-13 12:59:04.297] Sending broadcast ping for share 5678obfuscatedshare500[2014-02-13 12:59:04.297] Sending broadcast ping for share 0123ObfucsatedShare012300071[2014-02-13 12:59:04.297] Send ping to peer (01234567obfuscatedpeer000C99) for share 0123ObfucsatedShare012300071:[2014-02-13 12:59:04.297] ping xxWAN.IPxx.253.205:34780 directly[2014-02-13 12:59:04.297] ping xxWAN.IPxx.253.205:34780 via relay[2014-02-13 12:59:04.297] ping yyLAN.IPyy.63.13:61223 peer local address