I am trying to access a database (hosted in Azure) from a function app (hosted within the same Azure account).

I get the following error:
An exception has been raised that is likely due to a transient failure. Consider enabling transient error resiliency by adding 'EnableRetryOnFailure' to the 'UseSqlServer' call.

If I add EnableRetryOnFailure , it eventually returns with a timeout.

I have the following in my program.cs file:

string connectionString = Environment.GetEnvironmentVariable("DefaultConnection");

services.AddDbContext<VladbContext>(options => options.UseSqlServer(connectionString), ServiceLifetime.Transient);

We are using .NET 7 and Entity Framework Core. The EF Core code is shared with a Blazor app that works perfectly fine. The function also works fine on my local computer (connected to local database).

What could be the problem?

Update--------------------

Here is the error from the logs
"Exception: System.AggregateException: One or more errors occurred. (Retry failed after 4 tries. Retry settings can be adjusted in ClientOptions.Retry or by configuring a custom retry policy in ClientOptions.RetryPolicy. (A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. (ourserver.vault.azure.net:443)) (A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. (ourserver.vault.azure.net:443)) (A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. (ourserver.vault.azure.net:443)) (A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. (ourserver.vault.azure.net:443)))"

Update 2------------

We have now enabled SQL server to access keyvault (no idea why it needed to do that but hey)

We now get the following error in the logs instead.
2023-12-28T14:26:58.830 [Error] An error occurred using the connection to database 'ourSQLdB' on server 'tcp:ourSQLserver.database.windows.net,1433'. 2023-12-28T14:26:58.892 [Error] An exception occurred while iterating over the results of a query for context type 'App.DataService.Models.VladbContext'. System.InvalidOperationException: An exception has been raised that is likely due to a transient failure. Consider enabling transient error resiliency by adding 'EnableRetryOnFailure' to the 'UseSqlServer' call. ---> Microsoft.Data.SqlClient.SqlException (0x80131904): A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 0 - A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.) ---> System.ComponentModel.Win32Exception (10060): A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. at Microsoft.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)