Shocknet provides a simple way yet very quick and effective way of creating dedicated servers for GameMaker games. Shocknet servers are written in Javascript and ran with Node.js while the clients are made with GameMaker Studio 2.
Installing Shocknet is easy. Create a directory for your server and run npm i shocknet --save inside of it.
A full guide for getting started is in the works, but for now you should be able to figure out how it all works by reading through the example and Documentation.
Documentation for both the client and server sides of Shocknet can be found here.
The client side scripts for GameMaker Studio 2 can be found in the Marketplace here.