Help with IKEv2 VPN Connection Error: NO_PROPOSAL_CHOSEN

I’m currently having trouble setting up an IKEv2 VPN connection on an Android device using strongSwan as the VPN server. Despite having a valid certificate and key setup on both ends, I keep getting the error "NO_PROPOSAL_CHOSEN" in the logs when trying to establish the VPN connection. **Details of the Issue:** - VPN Server: strongSwan (on a Debian 12 VPS) - Client: Android 13 (using native VPN client) - Error Message: Oct 13 18:22:29 m1 charon: 12[CFG] looking for an IKEv2 config for 172.28.204.140...103.82.15.193 Oct 13 18:22:29 m1 charon: 12[IKE] no IKE config found for 172.28.204.140...103.82.15.193, sending NO_PROPOSAL_CHOSEN **VPN Server Config (simplified)** conn ikev2-vpn keyexchange=ikev2 ike=aes128-sha1-modp1024! esp=aes128-sha1! left=XXX # Server's public IP address leftcert=/etc/ipsec.d/certs/serverCert.pem leftsubnet=0.0.0.0/0 right=%any # Dynamic client IP rightdns=8.8.8.8, 8.8.4.4 rightsourceip=10.10.10.0/24 rightauth=eap-tls rightcert=/etc/ipsec.d/certs/userCert.pem leftauth=pubkey leftid=XXX auto=add **What am I missing or doing wrong?** Has anyone encountered this error or knows what might be causing the issue? Any suggestions or guidance would be greatly appreciated! Thanks in advance!