@Pauline: IP 64.20.61.146 is still blocked.
Thanks, but i am not going to make exceptions to our firewall. (I'd rather wait until your server gets de-listed) We are still able to use the software on a laptop connected to our guest-wifi that breaks out through a seperate internet-connection.
@peter and @alain: changing versions are probably not the "culprit"; I guess there might also be some firewall blocking above IP-address in your enviroment. It could be coincedence.