Summary

The initial SQL Server database connection fails.

Error

Server not found.

Login failed.

Cause

The database server no longer knows the connection to the domain.
Check your Windows Defender Firewall.

Solution

Restart the Windows service Network Location Awareness.

Solution 2

In very rare cases you have to enter the IP together with the port, e.g. 12.345.67.890,1112.
Your hosting provider may have enabled multiple SQL databases through this connection and the connection needs to be specified in more detail.

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