Hi!
You can ask your ISP for a static ip, depending on the ISP it might have an extra cost but it should be possible.
Because even if you use a tunneling service most of the will change the ip address or domain name given when you restart the service, the only one that will give you a fixed doamin name is portmap.io, but you can use only 1 tunnel in the free version.
Check this articles and video:
Greetings!
Diego
