KB4190: Failed to verify the connection to SQL Server
https://www.veeam.com/kb419029.09.2021 · In case of the SQL Managed Instances, enable the public endpoint in the instance networking options and then configure the security group of the network where the SQL Managed Instance is connected. If there are any other firewalls between Veeam Backup for Azure and the SQL Servers or SQL Managed Instances, they must be configured as well.
Staging SQL Server - Veeam Backup Explorers Guide
helpcenter.veeam.com › docs › backupApr 14, 2021 · To perform Microsoft SharePoint items recovery, Veeam Explorer requires a Microsoft SQL server to be used as a staging system. The server you are going to use as a staging system must conform to the following: A staging system must have the same or later version of Microsoft SQL Server that hosts restored Microsoft SharePoint databases.