Hello! I have end_remastered, betterendisland and better end installed.

I opened the portal and started the fight, however the dragon despawned instantly, opening the end portal but creating a glitched end gate version, with no portal and only two end walls flying.

I tried deleting my DIM1 folder to reset the end and it generated a end island with no dragon or structure, only with the pillars from your mod.

I read somewhere here about a command to reset the island but that command does not exist on my game.

Can you help me please?

Issue seems to be incompatibility with e4mc / lan server settings, removing both the ender dragon started spawning, however he seems to fly up and stay out of reach for some odd reason.. but the issue was fixed removing the two mods mentioned alongside with better end island and i had to delete my DIM1 folder on the map files for it to create the end island properly.
(better end also creates custom towers so it only worked properly after resetting the files, even before loading the end for the first time on backup world or else the better end island's towers were there, but with no bedrock "nest", central structures or end crystals.)