all what you have to do to host a server.
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- get the gdtmp mod and the ultimate lib mod (at steamworkshop)

- then start game dev tycoon aktivate the mods and resart the game

- when the update window open then click cancel.

- get the latest server file here ( The new server can be found at:
https://mega.nz/#!spBjRCqR!s9smHCZyscuaAOQZbxS7AwXy69xbdMlYmaR1svpzoAo ) and extract it anywhere on your PC.

- start dmultiplayersrv.exe in the extracted folder (this is the server) you can ignore all errors.

- Start game dev tycoon

- when the update window open then click cancel.

- start a new game, go into options, and click on switch server.

- type in your public ip AND your server port ( you can get your public ip at example here https://www.whatismyip.com/ ) like 84.104.24.3:1337 the click "direct connect"

- Thats it



all what you have to do to invite Friends (or connect to a host)
--------------------------------------------------------------

- your friend have to get gdtmp and the ultimat lib mod (at Steamworkshop)

- then start game dev tycoon aktivate the mods and resart the game.

- when the update window open then click cancel.

- start a new game, go into options, and click on switch server.

- type in the IP. from the server host like 84.104.24.3:1337 then click "direct connect"

- thats it.

_________________________________________
port forwarding

if you still can´t connect
make a rule for portforwarding for Port 1337 (serverport) and 3966 (clientport)
please serach with google or something else for your router type.


this steps works for me, and can connect a PRIVATE server for me and my friends.

mfg
Duddnkarl