It is enitirely possible that the connection is refused because the server/network to which your are trying to connect just doesn't recognise/accept the IP range used by your ISP.
This could be oversight, or because the ISP has new IP ranges, or simply because a lot of insecure/abusive connections have been noted from that IP range in the past.
Try writing to the server admins asking (politely!) why you are unable to connect, and - if one of the first 2 possible reasons is true - whether it would be possible to rectify the situation.
PM
