linux – Cannot access Apache Server from outside

I have a Raspberry Pi 4 with Raspberry Pi OS Lite and I have set up there an Apache server following this tutorial. However I can only reach this server either through LAN or a private Wireguard VPN, and I want to access it through my public IP. Neither port 80 nor port 443 seem to work.

At first I thought it might be a problem with port forwarding, I’ve read that some routers or ISPs block ports 80 and 443, but I’ve tried to start a simple HTTP Python server on my personal PC (using python -m http.server <port> where I replaced <port> with 80 and 443 to test both) and I could access the python server querying my public IP address, so I guess port forwarding is working.

That only leaves me assuming that either the Apache configuration is wrong or the firewall is blocking it? I haven’t manually set up any firewalls on the Raspberry Pi so any kind of configuration in that regard is the default one, and the Apache Config I’d say that it is also the same, so I don’t know what might be happening.

How can I “debug” this?