Registry Service Unreachable

Terraform Enterprise (Latest version) under a restricted network
Vault Provider (Default version)

I am trying to run terraform code using Vault provider on the root module, I am using a proxy to reach the outside world , but I am getting the following error:

Registry service unreachable.
This may indicate a network issue, or an issue with the requested Terraform Registry.

Error: registry service is unreachable, check for status updates

This issue starts when it tries to initialize the provider plugins, has anyone come across this issue?