Diablo 1 HD Hellfire Mod | Awake

Hello. I'm trying to get Diablo 1, Tchernobog working on multiplayer so that my roomate and I can play. We are both on the same WiFi network, and both have Windows 10 installed.

Whenever either of us hosts, the other cannot join. Specifically, the "join" button where you enter the IP address is grayed out and cannot be clicked.

I would rather not install new software or use a 3rd party solution like Evolve. Is there anything I can do or does Tchernobog just not work for multiplayer?

>Whenever either of us hosts, the other cannot join.

means can't join each other on same local network (not over internet) right ?
if so, try to run as administrator first.

F.Y.I.
You dont need installing VPN (like Hamachi/evolve) if you play on same local network only.
VPN is necessary when you want multiplayer player over internet.

That seems to be UAC/Firewall issue...