windows 11 network connections to local network

We cant reach any of our devices in the same network and they can’t reach our new windows 11 computer.

Pings do work fine, but http requests, curl and other requests do not.

I tried updating the network card driver … no success.
I reinitialized the network cards … no success.
I completely turned off the firewall … no success.

The other devices can reach each other, just this new windows 11 computer doesn’t.

Pings can reach the machine:

But e.g. curl does not:

C:Usersusername>curl http://192.168.0.163:5000/
curl: (7) Failed to connect to 192.168.0.163 port 5000 after 2051 ms: Connection refused

In Browser:

Localhost does work … and the server is running:

C:Usersusername>curl http://localhost:5000/
<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">

I Honestly don’t know what the problem is.
I asked the Microsoft Support, but they were no help at all.