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It's been a long time since I've worried about Direct IP support, and I never understood how UPNP worked.

If I have a public-facing IP address to my NAT gateway, will I still need to set up the port forwarding rules to my PC running the new/modernized version of Diablo if I want to allow an inbound connection to it in multiplayer, or will UPNP automagically handle the NAT traversal?