Use the software NO-IP. Register on the site, choose an external host name, example my-home.sytes.net, install the software on your computer and access the software with your beliefs.
Once accessed and logged in to the software, you will need to configure your router to route a certain traffic to your machine. In the case of a lodging, the important doors would be the 80 for access via HTTP, and 443 for access via HTTPS. I believe that just setting the 80 is enough for your case.
To accomplish this setting you will need the IP of your machine, as what will be done is redirect all the traffic that get at door 80 of your router to your machine.
To get your IP, open Command Prompt and type, ipconfig. Your ip should look something like 192.168.x. x, 10.x.x.x or 172.16.x. x.
Access the router and look for the port forwarding configuration or in English, port forward. You must inform in this configuration the IP address of your machine and also the input and output port. Both the input and output port will be port 80 and the IP address of your machine.
With everything configured correctly, you must configure xampp to respond at the address of the site you registered in No-ip.
I hope it is useful and can perform its configuration.
Possible duplicate of external access with wamp
– Guilherme Nascimento