Since playing Diablo 1 on Play Station as a kid and even in Uni days, I was delighted to hear Diablo was popping up on GOG and excited to spot it had online multiplyer.

I am desperately trying to figure out how to play it online so I can get some friends on for a nostalgic dungeon crawl, however after trawling through these forums and blindly mashing all the buttons in the classic version the furthest I can get to playing online is the in game chat rooms after it tells me I need to contact my ISP to open some ports or I won’t be able to play the game.

Everyone here is seemingly so knowledgeable about getting these things working that so far there has been no need for a guide in Layman’s terms. I’m happy to give third party software a try if that is the best route (I have seen Hamachi thrown around a few times) to simulate a LAN party but even that is a bit daunting for me! If it’s not simple enough, people just won’t play with me.

TL:DR – What is the simplest way for people to get started playing this together online? Any help anyone can provide would be greatly appreciated.

In my case, I did not configure any ports and the battle net online play mysteriously works when I leave and re-enter battle net after the port 6112 error message. The error message does not show up again when I re-enter.

I think this is how I got it to work in the past:

To configure firewall ports: us.battle.net/support/en/article/7842

To configure those ports on your router:
1. Type ipconfig on command prompt
2. Copy the "Default Gateway" IP address to your browser
3. Log into your router and configure the ports (Your router might have default login information that you can look up if it's not manually set. If you need to, there might be a way to reset your login info by holding a button on the router. The log in screen or physical router will give you the router model information that you can use to look up any instructions on Google if you need them.)

I'm having the same issue, I'm really disappointed in my purchase so far. I have tried every resolution to no avail; I continue to receive the udp port 6112 error and I am unable to create or join games when logged into battle.net. The whole point of buying this was for multiplayer and so far it has been a complete waste of money. I wouldn't recommend anyone buy this game until this issue is resolved. Total waste of money.

I had to foreward both TCP and UDP ports 6112-6119 to get it to go online, have not had a problem since.

Check out Hamachi or Gameranger. Both have worked great for me. It's 3rd party software, sure, but it gets the job done.

It's been awhile since i used Gameranger but it is more user friendly than Hamachi in my experience. If you want easy and only want to play private games with friends, i'd give it a try.

Thanks for the info Noobstorm.
I managed to get into the router and found the add service bit.
I have assumed that adding a service for "TCP/UCP" is the same as adding one each for "TCP" & "UCP" seperately.

I tried the battlenet route again and still got the message about chat only, then backed out and, out of interest, tried it again and it went in without flashing up the error. I didnt have anyone to try and join a game with at the time so I don't know if I had bypassed it or not :\ .

I have been reading into Hamachi which looks quite simple but heard rumors it can drop your connection, and annoyingly my friends would rather not download more third party software on top of GOG (but are happy to rummage around in their router settings??).

I think I agree with bdw2250, it's a real shame that even the revamped version doesnt even have a simpler route to playing online out of the box. We are very spoiled these days with how easy it is to join freinds in most games, no need for mid-advanced computing knowledge, but also quite lucky we have forums and google to help us get it working.

Sounds like you got it working. I'm glad to know this. Some people have been saying the error flashes up only the first time entering battle net on a Diablo instance. Happens to me as well.

Me and some other developers have worked on a mod that adds proper TCP/IP support with encryption to the game, this allows you to connect directly over the internet without the use of bnet, Hamachie etc. The only requirement is that the host must expose (port forwarding) port 6112 for TCP trafic. That might be more to the taste of your frind :)
https://github.com/diasurgical/devilutionX/releases