Access chat+ through main website only

I have been trying to block access to the rocketchat domain to all internet users except through the dolphin website. Can this be done?

I have tried blocking ports 80/443 using UFW (uncomplicated firewall) and adding the following firewall rules:

80                         ALLOW       122.255.113.26 (dolphin/example server IP)

443                       ALLOW       122.255.113.26

But then neither internet nor dolphin can connect to rocketchat.

I have the two servers within the same private network but rocketchat requires connection through domain/url and so restricting access to all IPs and allowing dolphin server only via internal IP wouldnt do the trick.

And as fro above the firewall doesnt seem to solve the issue. Maybe something could be done with the DNS records or within the apache virtual host, I am not sure.

Any pointers appreciated. Thanks.

Actually that is the default behaviour so I was making a problem where there wasnt one. My bad.