Not able to connect to external servers

The connection hang/timeout specifically happens on worlds that have Experimental Features enabled in their level.dat (such as Beta APIs, Holiday Creator Features, or Upcoming Creator Features).

My testing process:

1. I run a server with a few custom Add-ons.

2. After the 1.26.30 update, players would get stuck on "Connecting to the server".

3. I manually updated all my packs manifest files, bumping the min_engine_version to 1.26.30 and migrating the scripts from the beta API to the stable API.

4. Despite the code being fully updated and stable, the server still refused player connections.

5. The fix: The only way to let players join again was to completely disable the Add-ons and replace the world's level.dat with a Vanilla one (with all Experimental toggles turned to false/0).

Conclusion: The 1.26.30 BDS update seems to have completely broken the handshake or world-loading process for any server trying to load a level.dat that has creator experiments toggled on.

Temporary Workaround for other Admins: If you want your players to be able to join right now, you must disable your experimental Add-ons and turn off the experimental toggles in your level.dat (playing purely Vanilla) until Mojang releases a hotfix.

If I change transport=raknet to nethernet in server.properties it fails to connect more quickly with “Multiplayer Connection Failed” message:

With raknet the connection times out:

I didn’t see Smity’s comments before making my last.
But, I don’t have any experiments or add-ons enabled for my world. I think the log corroborates this but please let me know if there’s something else specific I should check:

Yeah, I just put in a new level name in server.properties causing it to create a new world, but I have the same problem.

One time, I was able to enter the server after I removed the addon and set the world spawn to a far coordinate, then restarted it. I was able to join once, but when I restarted the server again, I got stuck again.

This happened to us on two servers on two different hosts. One was pure vanilla, the other had minimal behaviour/resource packs. We fixed it by replacing the level.dat file with one from a fresh install, adding back in things like player sleeping percentage and days played (adding currentTick data from the original level.dat with time add) in the console. We took a backup of course, just in case everything went poorly, but both servers are up and playable now.

I’ve tried a new install in a new folder and cannot connect. This is across my own local network.