The server is 2b2t.org. I think it is using Waterfall or Paper spigot. Force using protocol 340 (1.12.2) results in a disconnected message.

In my experience, It's been kinda in an on-and-off state, where it'll sometimes work (Only twice so far) or disconnect before queue

Attached is a screenshot of the few times it was working, but we'll be looking into this:

Thats actually used to be it's own category on the roadmap haha

I recognize those coords see you soon

Jk, Thanks for the update!

Update for @Mhowser

In recent developments and in testing, I have found that if you don't use Fabric API, you'll be able to connect much more frequently without issue. While this is only a workaround, rest assured, the issue will be looked more closely at between multiconnect and Fabric API before an official release.

That's good to know! I also use brandpacket to change my client brand to "vanilla" which helps with restrictive servers.

I am having a similar issue, i am unable to override the client version on some waterfall servers, uses 1.16.2 even if i specify 1.12.
Not sure if i should create another bug report or not.

@OrangeCatSeth you should always be able to force the protocol to 1.12, even on waterfall servers, so this sounds like a separate issue. Mind creating a separate one for it?