How do I specify what port to use?

Why do you need to specify what port to use? Short answer: you can't change the port directly. There are a few workarounds.

1. Using service's default port

   Certain services use a default port, which they will try to conenct to first. For example, if you're hosting a minecraft server on the default port (25565), you most likely don't have to specify the port, since Minecraft automatically tries connecting there first.

2. Using a reverse proxy (such as NGINX)

   If you are running a webserver, you can use a reverse proxy such as NGINX to redirect your requests. Here's an example where NGINX redirects requests from port 80 to 8080

   server {
       listen 80;
       server_name example.frii.site;
   
       location / {
           proxy_set_header   X-Forwarded-For $remote_addr;
           proxy_set_header   Host $http_host;
           proxy_pass         "http://127.0.0.1:8080";
       }
   }

3. Manually specifying the port along with your domain

   If neither of thesae work, you can just simply use your port along with your domain using domain.frii.site:port. Example: mydomain.frii.site:5050 would use the IP of mydomain.frii.site and port 5050