SharePoint SE – Unknown SQL Exception 18452 occurred. Login failed.

This month we applied OS updates to the DB Server. Site was up. Then we applied OS Updates to App server, site went down and we reverted it. Then we applied OS updates on WFE server. The site is up. However, in WFE when running Get-SPFarm or running PSConfig on the WFE, it throws the following errors:

PowerShell / PSConfig: “Cannot access the local farm. Verify that the local farm is properly configured…”
Configuration Wizard: “Failed to detect if this server is joined to a server farm.”
The Error Logs:
Checking the Windows Event Viewer on the WFE during a database connection attempt shows:

Unknown SQL Exception 18452 occurred.
Login failed. The login is from an untrusted domain and cannot be used with Integrated authentication.
Network connectivity is fully operational.

AD Domain trust is healthy.

Local machine groups are clean: NT AUTHORITY\SYSTEM is not present inside the local WSS_WPG or IIS_IUSRS groups.
DisableLoopbackCheck is already set to 1 in the registry.

Any help on how to get the error is greatly appreciated.