Why Is a VPN Connection Always in Not Connected State After Its Configuration Is Complete?

The configuration may be incorrect.

1. At the two ends (cloud and on-premises data center) of the VPN connection, ensure that the pre-shared keys (PSKs) and negotiation information are consistent, the local and remote subnets are reversed, and the local and remote gateways are also reversed.
2. Ensure that routes, NAT, and security policies are correctly configured on the device in your on-premises data center.