quick question, is it possible to make an custom ip like play.servername.net or something?
See “dedicated ip” option under addons:
This gives you your very own IP address (#.#.#.#) so that you don’t need a custom port number (#.#.#.#:####) but it does not give you a domain (like example.org). You have to buy your own domain separately through any domain registrar such as Google Domains, GoDaddy etc. Then you point the root of the domain (example.org) or any subdomain (play.example.org) to your dedicated IP.
Say you were to buy a domain and point it to your IP without buying a dedicated IP. Then you’d still need to include the port number and your server address would look like example.org:654321