When I test this on the link mentioned in my previous post, it uses the port in the link, which in this case is +6697. This is different from my active server port, which is 6667.

Can you please confirm: in the link request dialog, under "mIRC has been asked to connect to:", I see "irc.freenode.net:+6697 #mIRC". What do you see in your link request in this location?