a "Connection refused" simply means that you attempted to connect doing everything correctly, and for whatever reason, the remote host responded with a TCP Reject packet. As to why they might have rejected your connection, I can only guess. There may have been a device somewhere in the middle that might have also rejected the connection (a firewall someplace... or content-filtering service... or several other possibilities)
As it is a fairly public resource, I doubt it has anything to do with their network blocking your connection. Perhaps your ISP doesn't allow connections to SVN (port 3690)... or the place you are connecting from limits connectivity for security reasons...