I may have found a fix for some (only tested on Bedrock). If you are upgrading an existing server and suddenly cannot connect (I tried updating from 1.26.23.1 to 1.26.30.5 and then again to 1.26.31.1), the issue may be caused by the hidden LANBroadcast flag in your world's level.dat file. Apparently older files often have this set to 0, which triggers a bug in the new server version that prevents it from broadcasting to clients.
As noted by @amorelli , you can open the world in a local single-player game which then flips the flag to 1. Alternatively you can edit the flag directly in an NBT editor. Here are the steps I used:
Download and extract1.26.31.1 files to a your desired directory.
Copy your entire existing world folder including your level.dat and your db folder) and paste it into the new server's worlds folder.
Do standard setup (I only know the basics like replace your allowlist, replace permissions, and configure server.properties and update level-name to match your world folder name.
Optional: You can temporarily change online-mode=false and allow-list=false... not sure if it’s need to bypass the bug, but it may help eliminate authentication roadblocks during a first test boot.
Use a bedrock NBT editor (or Java if applicable… not sure if this bug applies there). I used w1zardz Bedrock NBT Editor in a web browser so as to now have to download anything.
Upload your previously working level.dat which should (according to my steps) be located inside your newly copied world folder in the new server directory.
Scroll until you find the LANBroadcast variable. Double-click its value and change it from 0 to 1.
Click save/download to get the updated level.dat file. Now replace your new server's level.dat file with the new one you just downloaded.
Boot up the server. You should now be able to connect successfully from your local network!
If you did the optional online-mode and allow-list disabling, you can now open server.properties and change online-mode and allow-list back to true, and restart. Your server should now fully updated and accessible externally.
Droid Number 3
I may have found a fix for some (only tested on Bedrock). If you are upgrading an existing server and suddenly cannot connect (I tried updating from 1.26.23.1 to 1.26.30.5 and then again to 1.26.31.1), the issue may be caused by the hidden
LANBroadcastflag in your world'slevel.datfile. Apparently older files often have this set to0, which triggers a bug in the new server version that prevents it from broadcasting to clients.As noted by @amorelli , you can open the world in a local single-player game which then flips the flag to
1. Alternatively you can edit the flag directly in an NBT editor. Here are the steps I used:Download and extract1.26.31.1 files to a your desired directory.
Copy your entire existing world folder including your
level.datand yourdbfolder) and paste it into the new server'sworldsfolder.Do standard setup (I only know the basics like replace your
allowlist, replacepermissions, and configureserver.propertiesand updatelevel-nameto match your world folder name.Optional: You can temporarily change
online-mode=falseandallow-list=false... not sure if it’s need to bypass the bug, but it may help eliminate authentication roadblocks during a first test boot.Use a bedrock NBT editor (or Java if applicable… not sure if this bug applies there). I used w1zardz Bedrock NBT Editor in a web browser so as to now have to download anything.
Upload your previously working
level.datwhich should (according to my steps) be located inside your newly copied world folder in the new server directory.Scroll until you find the
LANBroadcastvariable. Double-click its value and change it from0to1.Click save/download to get the updated
level.datfile. Now replace your new server'slevel.datfile with the new one you just downloaded.Boot up the server. You should now be able to connect successfully from your local network!
If you did the optional online-mode and allow-list disabling, you can now open
server.propertiesand changeonline-modeandallow-listback totrue, and restart. Your server should now fully updated and accessible externally.