this happened to me about a week ago my IP was auto banned because I used a proxy to log into cPanel too many times, right click on your network connection & click properties - security - advanced & make sure Enable Federal information processing standards is UN checked (that was my issue)
admin will need to un ban your IP
Our Firefall may have anti-virus/malware that is sensitive to blacklisted IPs. Could be that you are sharing an IP with a spammer/s. (It has happened to me too). Best way to get out of the situation is either to get a static IP which may be very expensive, or to use a VPN.
Have fixed it Yozora. Let us know if it is OK now. :good:
Un4saken suggests that if you restarted your router you can get a new IP that way. Maybe you could try that instead of trying to get the IP removed from the blacklisting. And of course check the new IP as well.