It sounds like you’re connecting to an ancient version of SQL Server that doesn’t support at least TLS 1.2.
See Error connection SQL Server database after upgrade Ignition - #2 by Kevin.Herron and https://support.inductiveautomation.com/hc/en-us/articles/4417310204813-TLS-v1-0-and-v1-1-Microsoft-SQL-Server-Database-connection-issue