This is very weird...
So I've disabled Windows Firewall, and enabled logging on my router, and it looks like the packets are at least going through my router.
When I (attempt to) connect I get:
Sun, 2014-12-14 20:44:10 - TCP Packet - Source:192.168.0.4,53797 Destination:62.113.223.150,6112 - [Warcraft II rule match]
Sun, 2014-12-14 20:44:11 - UDP Packet - Source:192.168.0.4,6112 Destination:62.113.223.150,6112 - [Warcraft II rule match]
Sun, 2014-12-14 20:44:11 - TCP Packet - Source:192.168.0.4,53797 Destination:62.113.223.150,6112 - [Warcraft II rule match]
So is the only thing left my ISP blocking my packets? But how can I still connect via telnet?
I'm utterly confused...