Uh… you can’t just “expose a LAN network to the Internet” in this manner. Local subnets aren’t routable over the Internet, so you can’t just enter 192.168.2.3 and end up on somebody else’s private LAN.

geeksforgeeks.org/…/non-routable-address-space/

They would have needed to either have all their internal devices being assigned public IP’s or had NAT+firewall rules explicitly routing ports from their outside address(es) to the inside ones. The former is unlikely as normally ISPs don’t allocate that many to a given client, or at least not by DHCP. the latter would require a specific configuration mapping the outside addresses/ports to inside devices, likely on a per device+port basis.

Either your story is missing key details or you’ve misunderstood/made-up something.