Duckdns, Dnsmasq, NGinx proxy, and loopback question

I am about 99% of where i want to be when it comes to device trackers and presence detection. Having DuckDNS working with the NGinx proxy, and able to access hassio outside of my network, the one thing that still I can’t get past is the loopback issue. I have installed DNSmasq and I can access my local home assistant via duckdns address, but the problem lies with the phones (iOS app) which travel in and out of the network location.

Using default port 443 works great with no separate configurations necessary inside or outside of network, but when i route a different port to 443 on the rpi running hassio, what happens is that I have to specify the custom port at the end of the duckdns address while out. When I return home, if i want to use the app on my network i have to remove the custom port and resave giving me access to home.

I was wondering if there is a setting where i can have the custom port be recognized in the home network, or a code that would allow me to forgo the port specification while I am away. Thanks.