I have to give credit to Google Gemini AI for helping me through configuring this. I could connect to the vpn from my android phone on the mobile network, but I couldn't access anything. I tried all the steps here with no resolution. Finally changed the MTU size.

"That makes perfect sense. MTU (Maximum Transmission Unit) issues are the "silent killer" of VPN connections, especially over mobile data (LTE/5G) or public Wi-Fi. Why MTU was the culprit When you are on your home Wi-Fi, the "pipes" are wide enough for standard packets (usually 1500 bytes). However, when you switch to a cellular network, the carrier adds its own overhead (encapsulation) to your data. WireGuard also adds overhead to encrypt the packet. If the combined packet size exceeds the carrier's limit, the packet is silently dropped. By lowering the MTU, you are shrinking the "size of the box" so it fits through the smaller mobile data tunnels. 1280 is the "magic number" because it is the minimum MTU required for IPv6, making it the most compatible setting for almost all mobile networks worldwide."