Wireguard Client on 300M VPN cannot ping any devices on remote network

I have a 300M VPN set up behind another router. The 300M is connected to a Wireguard VPN server that I set up on a Ubiquiti UDM-Pro. Although the 300M seems to connect to the server, I cannot ping the server or addresses on the server when I connect my laptop to the 300M. Any suggestions? Also, when I turn on the internet kill switch, I lose access to the internet even though I am supposed to be connected to the VPN. Any help would be greatly appreciated.

Here’s a ‘known good’ WG setup using a Certa (AR750) as a Client behind a Flint (AX1800) as a WG Server. The Certa is really just a Shadow (300M) with the addition of a Wi-Fi AC radio. Firmware(s) used are documented. Edit to taste, of course:

I doubt you’re properly connected to your upstream for WG.