Can you clarify what do you mean when you are talking about hosted software on a Google Cloud VPC? Are you talking about a GCE instance using a VPC network with 'Solr search' standalone software installed? What do you mean when you are saying that you are not able to connect to google cloud when you are 'hosting' your .NET code to cloud? Are you trying to connect to a specific resource in GCP (e.g.: GCE instance, APP engine, Cloud SQL)? Are you using a Cloud VPN and you want to access from your on-premise site to a GCP service?
'The Virtual Private Cloud (VPC) provides networking functionality to
Compute Engine virtual machine (VM) instances, GKE containers and App
Engine Flex. VPC provides global, scalable, flexible networking for
your cloud-based services.'
The VPC networks route, allow or deny network traffic, it's difficult to install software on it. Try to describe better your issue,e.g.: instance not accessible by API through Cloud VPN. If you are using an instance for your software:
- Check if the instance has the correct configuration to use the API.
- The firewall rules are allowing the network traffic to the correct IPs and Ports.
- Check the routes from your on-premise site to the VPC network where the Solr instance is.