Moonwalker,
When using SSL/HTTPS, you should always use the right domain name in the URL. Otherwise, Abyss Web Server would not know which host will respond to your request.
Also, we have no idea about dynu redirection. From our previous experience with these service, you should always make them associate your dynu name with your IP address. Never use what they call redirection because it's a fake solution that won't work with virtual hosting and especially when you use alternative ports.
So configure dynu to associate your domain name XXXX.dynu.com (for example) with your actual IP address, and then your site will be accessible using
https://XXXX.dynu.com:4430 . The port number is required.
On your local computer, you should use one the suggestions in
https://aprelium.com/abyssws/articles/access-test.html to test your site locally. The workaround is required most of the time because of the limitations of routers.