Hi William,
Thank you for providing me your Ad Unit ID.
I tried using your Ad Unit ID on
the sample app and I can verify that I can receive ads on my end, so this is most likely a network and/or device specific issue on your end.
As for your Charles' Logs, make sure that SSL Proxying is Enabled, and your application trusts the SSL Certificate that Charles' provides, as stated on your screenshot. For your second concern, any VPN should work. However, would you be able to try to request ads without a VPN and verify if you are able to receive ads on your end?