The Shield Security plugin uses visitor IP address in many areas. Ensuring that the plugin can detect the visitor IP address accurately is an important step in the setup process.
Visitor IP address detection is unfortunately quite unreliable for most web hosting. The problem is that every host is a little bit different in their configuration and sometime they're not configured as well as they can be.
So, Shield provides a simple way to help with this. In the cases where the IP detection isn't functioning correctly, you can help Shield by telling it which source to use.
You'll see this option in Shield (Settings tab) => General => Plugin Defaults => IP Source:
There are a list of technical looking IP address sources. We will need you to pick the one that is correct.
If you don't know what your particular IP address is, please see here: https://onedollarplugin.com/my-ip/
Use the IP address printed on that page to select the source from the dropdown that is giving the same IP.
This will help ensure Shield is using the correct source for visitor IP addresses.
Note: If you can't change the IP source, please read the article here.