Cannot modify port, windows port setting problem

Why I cannot modify FLASK port

#cmd
WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead.
 * Running on http://127.0.0.1:5000
Press CTRL+C to quit

I used serve or app.run() and set port=5566, always not work

#index.py
if __name__ == "__main__":
    from waitress import serve
    serve(app, host="0.0.0.0", port=5566)
    #app.run()

I set windows11 fire wall input/output rule, all allow, port:5566 ,but system show me didn't open the port:5566

And at server pc type "http://127.0.0.1:5000/" I can upload image by FLASK,server pc can get the image, but will appear "Internal Server Error" lead to I cannot return anything.

Other user type "IP" can connect to website but cannot upload image, type "IP:5000" or "IP:5566", cannot link to website

Solution

Try running it from the command line.
(I mean the windows one not one built in to an editor)
According to this question, it helped.
To do this, open a command prompt by pressing WINDOWS + R then typecmd.
Then type python <yourscript>.py
Also try running the command promt as an admin.