Thanks for the great effort !!!
as you say , the EOS should not be the root cause that other can not join
I try "crossplatform=None" and run the server over and over again but still can not join
and I turn off the firewall but still not works
finally I reinstall the ubuntu , can join the server.
I think fail joining server due to some network config
the EOS error still can not fix , if the game runs well , let it go