unable to join lan single player world

i have a main computer running Minecraft  1.16.4 i started a new world and opened up a lan so my daughter could join in on my world, then i have just bought a laptop so my son could also join, but when i went to multiplayer on the laptop the world shows up but i am unable to connect to it (Failed to connect to the server - disconnected), i have tried disabling fire wall, security made sure im on a private network etc, however when i load 1.16.5 and launch a lan i am able to join the world on the laptop, it seems to be just with 1.16.4 although no issues doing it with my daughters pc, please help as now have a useless laptop as only got for this reason