Thanks for the explanation, Mick. I've encountered this problem a few times while using my phone on the mobile network. On the other hand over here usually an IP address of a DSL connection is reassigned every 24 hours, or after reconnecting the router. If some bad guy abuses his connection and the IP address gets blacklisted, some other day someone else may get this address. Reconnecting to the internet in order to receive a new address is a good idea to solve the blacklist problem.