I just started using wireguard, after using openvpn for quite a while. I've seen a semi-regular bug when using wireguard from Windows 10. I find if I switch from one vpn to another, by deactivating one and activating another, and then I switch back to the first one, I often find that I can no longer connect to servers in that 1st vpn. I get the handshake, but can't actually connect to anything after that - perhaps some issue with the Windows routing table?
Oddly, to fix it, I find that I have to edit the config in wireguard windows - e.g by changing the order of the lines in the text Then I find I can connect again. Even rebooting doesn't fix it - only editing the config (e.g by changing the order of the lines) works. It seems to happen with different servers in different locations, but here's a server conf dump if it helps: https://0x0.st/ilqo.txt Let me know if there's any other info I could provide.
