With IKEv1 used by L2VPN using L2TP/IPsec and L2TPv3, NAT traversal is supported by ESP tunnel in main mode and transport mode.

Does IKEv2 support NAT traversal?

Unlike IKEv1, which uses Phase 1 SA and Phase 2 SA, IKEv2 uses a child SA for Encapsulating Security Payload (ESP) or Authentication Header (AH), which is set up with an IKE SA. NAT traversal (NAT-T) must be enabled on both gateways if you have NAT occurring on a device that sits between the two gateways.

What is NAT Traversal?

Network address translation traversal is a computer networking technique of establishing and maintaining Internet protocol connections across gateways that implement network address translation (NAT).