ejabberd-contrib/mod_isolation

mod_isolation: Isolate virtual hosts from each other

The module blocks communication of users between different virtual hosts.

Configuration

The module doesn't have any options, so the simpliest way to configure is:

modules:
  ...
  mod_isolation: {}
  ...

Hint: if you also want to block whole s2s, use built-in ejabberd's s2s_access option:

s2s_access: none
...
modules:
  ...
  mod_isolation: {}
  ...