Run a python script when connected to internet

I have a simple python script hello.py and a hello.sh file:

#!/bin/bash
python -c "from hello import hello; hello()"

(hello.py is in PYTHONPATH)

made it executeable and placed in the if-up.d directory. Being in the directory and running ./hello.sh it works as it should. But disconnecting and re-connecting does not trigger the script.

Even it the script is just echo "hello">>out.txt it still doesn’t get executed. My user is owner of the script (running ubuntu 20.04)

Any idea?

 #!/bin/sh 
    if [ "$IFACE" = <interface-name> ]; then 
        python <path_to_your_script>.py
    fi

sudo chmod +x <path_to_your_script>.sh