How to ensure that everyone can access the port opened from the external network?

[taksimuncle]

Have a nice day. I use have a static IP. I did port forwarding and opened a simple Python HTTP server on my computer. I was thinking of being able to access this from the external network (for example, by opening a VPN), but I cannot access it from my own computer. (I may not be able to access it due to loopback). It gives a connection refused or timeout error. There is an exception that I can access it from my own phone both via Wi-Fi and mobile data(moreover, if i use vpn on my phone i can access also) . However, some of my friends cannot access it, some can. I'm not sure what causes the connection to fail and what doesn't. The firewall is not open on the modem. Windows security allows Python. I want everyone to have access. I would appreciate it if friends who understand could help.