Forwarding 2 devices with the same (Unchangeable) Port number: is it possible?

I'm a technician, but not an IT pro. I do locksmith/security primarily. I've been tasked with getting an access control system online, and it's normally not a problem. We've got a static IP from our ISP, and I usually just set up port forwarding and we're good to go. The system we have has port 443 assumed by the manufacturer (honeywell), but the network has a controls system that is already assigned to Port 443. The building management company says the port isn't changeable on their panel either. Is there any solution? We can add a router or something if necessary, I just can't find even where to look for the answer. Thanks for any help!