In the early stages of planning a migration to GCP, you wish to test the functionality of your hybrid cloud design before full implementation in production. This involves services running on a Compute Engine Virtual Machine instance that must communicate with on-premises servers using private IP addresses. Although the on-premises servers have internet connectivity, Cloud Interconnect connections have not yet been established. You aim to choose the most cost-effective method to enable connectivity between your instance and the on-premises servers, completing the test within 24 hours. Which connectivity method should you choose?