How to access internal servers using external, fqdn, address?

Hi, I'm new to Sophos XG firewall, installed and testing my first one.

My first task is to open some ports so that a Synology NAS can be accessed from both outside and inside.

I created some rules and everything is working fine from outside, but for my laptop and smartphone, when they are connected to the same office network as the server, they do not work with the fqdn, only with internal ip address.

I tried to check in the business application rule, Advanced, routing, the option Rewrite source address (masquerading) with no success.

Any idea ?

Thank you