I develop and maintain this custom modpack because a lot of the other Minecraft modded servers either didn't have quite the gameplay I was looking for, didn't have both a tech and magic progression line, tended to shutdown or reset the map after the server got large or old, or didn't have the proper compute power to host lag-free. I therfore develop NCP+, based on Continuum, but already pretty far forked. I want to enourage people to invest their time into large, complex builds, as I will not be resetting or deleting the server just because it's not popular for a time period or it gets old. I plan to maintain it as my personal pet project. My own game if you will, based on the Minecraft Engine. Everyone is free to join, provided they email me so I can add them to the whitelist.
Everything Micro$oft touches turns to shit. I refuse to let them have my game and gameserver too. This will NOT be the end of this.
I am currently looking for ways to fix it. As it currently stands, I can't play my own gameserver on my own launcher. I cannot just rip out all of the authentication code either as that would allow malicious users to log into other people's accounts to grief things. As I currently see the most viable option is going to have to be to switch out the primary server jar file, which currently is a vanilla jar modified with Forge ML. None of the authentication offerings on CurseForge seem to offer what I need for the basegame version I'm running (1.12.x) so I'm probably going to have to look at other APIs to accomplish this. I've played on offline servers that had a basic /register and /login command before, so I know it's possible and it's a thing people do. Ideally I'd have something like 2b2t's setup that can even prevent coordinate stealing, but I'm not sure if that is possible because I think they are using bunjeecord, which is some kind of reverse proxy server for minecraft. I don't think BC is compatible with forge modded servers. I have reached out to 2b2t's admins team but they have not responded. I am currently looking at Sponge (https://spongepowered.org/) as an option but am still investingating.
I think I figured out a solution that will work, but it involves making it a 'SpongeForge' server to implement an API needed for an authentication plugin. I am already in the process of carrying out this development work. There are a few problems however. The server's forge jar needed to be updated which breaks a lot of mods both serverside and client side, and the updates to those mods break other mods. Yes this is hell but this is what maintaing a modded minecraft server is actually like.
I have a working development version on my workstation right now that launches. I've still got more work to do bringing clientside changes back into the server and polishing up loose ends. Then I have to commit those changes to git. I'm going to leave the server offline until I can get a working release out since I can't connect to the server myself anyways.