This error message generally does not affect your WireGuard VPN connection — it simply means that netifd encountered an issue while restarting the WireGuard interface.
(After the first trying to connect to server, if timeout, netifd will restart the wg interface)
After the WireGuard VPN has started, could you please SSH into the router and run the following commands for further troubleshooting? (Remember to remove or hide your private/public keys before sharing the output with us.)
# Display WireGuard status
wg show
# Ping the IP address or domain shown in the WireGuard endpoint
ping example.com -c 4