I can't find any info about HeroNet blocking p2p. Their terms & conditions are a bit vague, but there's a mention of not infringing on copyright.

When you set up your port forwarding, did you use the instructions here: Port Forwarding for the Linksys WRT54GSv4 and did you set up a static IP address first?

You could also try changing ports. In LW tools > options > advanced > firewall config. Change LW's listening port to 65000 (or something in the range of 49152 - 65535) > apply > ok.
Now set up port forwarding for that new port number. LW's listening port, port in the 'manual port forward' box & port forwarded within your router's config should all be the same number.

You could also try updating your Java & deleting LW's preferences folder(s). More info about that here: If LW Will Not Connect