The problem, however, is it appears that the connection gets dropped after ~5min.
All timeouts on Filezilla Server are set to 0.
Firewall (windows) is off on this server.
WebFilter & IPS have exceptions for the server host.
I've tested long transfers to other FTP servers (godaddy) which go through fine.
Tested with another server (pure-ftpd) on a NAS behind this UTM, same problem.
This is what I get from frox debug log when using Non-Transparent:
2014:08:26-08:49:58 redrocker frox[19097]: S: 230 Logged on
2014:08:26-08:49:58 redrocker frox[19097]: C: CWD /
2014:08:26-08:49:58 redrocker frox[19097]: S: 250 CWD successful. "/" is current directory.
2014:08:26-08:49:58 redrocker frox[19097]: C: PWD
2014:08:26-08:49:58 redrocker frox[19097]: S: 257 "/" is current directory.
2014:08:26-08:49:58 redrocker frox[19097]: C: TYPE I
2014:08:26-08:49:58 redrocker frox[19097]: S: 200 Type set to I
2014:08:26-08:49:58 redrocker frox[19097]: Intercepted a PASV command
2014:08:26-08:49:58 redrocker frox[19097]: C: PASV
2014:08:26-08:49:59 redrocker frox[19097]: PASV: 67.198.x.x:5625
2014:08:26-08:49:59 redrocker frox[19097]: S: 227 Entering Passive Mode (67,198,x,x,219,219)
2014:08:26-08:49:59 redrocker frox[19097]: C: PWD
2014:08:26-08:49:59 redrocker frox[19097]: C: STOR 200MB.zip
2014:08:26-08:49:59 redrocker frox[19097]: Client has connected to proxy data line
2014:08:26-08:49:59 redrocker frox[19097]: S: 150 Opening data channel for file upload to server of "/200MB.zip"
2014:08:26-08:54:56 redrocker frox[19080]: Connection timed out.
2014:08:26-08:54:56 redrocker frox[19080]: Closing session
This thread was automatically locked due to age.