Can I access configured site by using ip from different port?

[NamekMaster]

I have other app listens 80/443 port on my NAS, so I changed the port mapping in docker-compose config file to others like 20080/20443, then I try to access 192.168.1.2:20080 but it only show the congratulation page. I also tried hostname:20080, I don't known why it's not working. Is it possible to do that?
I also tried config reverse proxy on my NAS (Synology) to proxy https://hostname to http://192.1658.1.2:20080. Is it possible to work?