If after an install or after relocating the database to a new server, the Simply Safety application can no longer connect to the database, check the following…
Using the SQL Configuration Manager, open the path to the Client Protocols for the Simply Safety instance and enable TCP/IP
Also, enable the required ports 1433 and 1434 (if using SQL Server,
or open all ports for the SQL Express application. To locate the path to the executable program, find the field in the Service that displays the desired SQL instance.
Refer to the following articles: https://www.mssqltips.com/sqlservertip/6511/sql-server-express/