My browser can't connect to my home server

I run some services on a home server, but I couldn't access them via my browser. I can ping the machine, use Curl to get the page content, but my web browser refuses to display a single page...

The first time it happened, I was too lazy to investigate why, and I got used to using ssh to create a tunnel between my laptop and my home server. But today, I was fed up, so I finaly did some research.

Is the problem due to Firefox?

By opening the inspector, it's possible to get the error in the "Network" tab:

NS_ERROR_CONNECTION_REFUSED... So, the error isn't caused by Firefox, but by macOS (NS is a NeXT Step heritage). Something at the macOS level is blocking the connection.

What are you doing, macOS?

The console output is not helpful, except confirming that my laptop blocked the traffic:

I admit, I got lucky while digging through macOS settings. Firewall? No, it doesn't block outgoing connections. Privacy and security? Bingo!

Turning on Firefox in the "Local Network" section solved the issue. No more need for tunnels!