new 1.14 version can't multiplay with lower 1.14

The player hosting the world will need to update to 1.14.60 also.

but when I in 1.14.30.2 I still can play with player in lower 1.14 or ever 1.14 beta

no, you need to be the same version

Hi Bui,

Whether an update is compatible with previous versions depends on the changes that are in the new version.

For example, if its just fixes for crashes that don't interact with the multiplayer component at all then they are fully backwards compatible, but if they change the code for opening a shulkerbox for example, the old and new code cannot work together so require an update.

In this case changes were made that were not backwards compatible. Best to ask your friend to update.

Ionic

where I can find a list of version can playable with each other

You might also try the Minecraft Community Support Discord at: https://discord.gg/58Sxm23

In general though, if everyone always has the latest release version (currently 1.14.60) then multiplayer should work.

I have same version, and i have permission to join, but I can't. Why?