You mean ?
Installing and upgrading help
moodle 2.3 and 2.4 installation error
I limited my load balancing with only one backend server and it's the same.
Maybe version 2.3 does not include reverse proxy method htat manage obviously different backend IP.
But anyway, I'm a moodle plugin developer so I would need to run version 2.3 and 2.4 to update my plugins.