If you your outgoing traffic is going over a proxy server in your network, you have to pass this server along to the piplanning app.
You can set the Proxy URL inside the app by doing the following:
It might also work without "http(s)://" at all.
Tip: If using your networks proxy server directly does not work, you could try installing a local proxy server which connects to your network proxy. Connect then your piplanning app to the local proxy. (CNTLM proxy)
There are multiple ways to set an environment variable. Check out this guide to see how you can set a environment variable on Windows: https://www.computerhope.com/issues/ch000549.htm