I think you can try to do that by configuring your HTTP server and DNS this way, assuming you’re using Apache:
This way, the same mautic installation is available from two different sub-domains. There is sill one important issue to be solved: an appropriate cookie domain. I think you will also have to set the mautic.cookie_domain configuration parameter to domain.com in config/local.php, so that the same tracking cookie is used both on mautic.domain.com and lp.mautic.domain.com.
If you want to have SSL support, then it will be a little more difficult, you may either:
- use a wildcard certificate *.domain.com that will match both the main name and the alias with a single certificate.
- instead of using ServerAlias, create a second vhost lp.domain.com, pointing to the same PHP code as the main vhost, but configured with a different certificate.
This should work but it’s just an idea, completely untested…