Connection to MSSQL(2014) lost when updated to 8.1 (from 7.9)

This thread (and its linked threads) should cover your SQL Server problem: SQL Server Connection Faulted

Basically, your old version of SQL Server does not support TLS 1.2, and by default newer Java versions have deprecated and do not support TLS 1.0 or 1.1. So you either need to upgrade SQL Server or hack up your Java install to enable the insecure protocols.

User sources are managed in the gateway. All I know is you have a user source trying to a connect to an AD server at hostname “scada-dc”. Classic Authentication Strategy - Ignition User Manual 8.1 - Ignition Documentation