We have the Azure App Service set up to host a portal with an ASP.Net Core backend.
The Backend then connects to Business Central using OData V4 to Store and Retrieve data as required.
The portal has been running for over a year with no issue.
The problem we are facing:
We were using Basic Authentication until Saturday when our Business central Updated and Basic Authentication was no longer supported.
We updated our backend to make use of Microsoft.Identity.Client Library to get new OData Access Tokens to connect to Business Central.
We experienced issues with the request to get new tokens returning an error of "No such host is known", We figured it was an issue with the code and found another way to handle Access tokens.
Shortly after we noticed that all outgoing requests are throwing the same exceptions.
Both "HttpClient" and "HttpWebRequest" fail with the same error.
When Running on local development IIS we have no issues.
No changes were made to the App Service Configuration we had originally.
We don't have a VNet setup, My understanding is that this is only used to make requests to other resources on the Vnet and not to external services.
We also did not have any issues at all before without this setup.
