For a version that works for pre 1.9, check out marinersfan824's backport: https://github.com/marinersfan824/Force-Port-Mod/releases
Force port forces the open to lan port to be 25565 (the default server port for minecraft).
Additionally it increases the player limit of an open to lan world to be unlimited.
Mod built for 1.16.1 but may work for other versions. (Open an issue to request a version that doesn't work)