Cisco Umbrella uses the IPsec protocol for tunneling traffic. IPsec has multiple components and one of the key components is IKE, which manages negotiation with the peers, authenticating, certificate exchanges and also maintains the session by using the keepalive mechanism. Umbrella only supports IKEv2, which is faster and more secure than IKEv1.

Enable Block Page Bypass in a Policy < IPsec Configuration > Supported IPSec Parameters