Windows Remote Desktop Services - Gateway Role

Windows Services

Remote Desktop Configuration

Remote Desktop Gateway

Remote Desktop Services

Remote Desktop Services UserMode Port Redirector

Terminal Services Gateway Performance Counters

Connection request authorization timeShows the average connection request authentication and authorization times in seconds.
Current connectionsShows the total number of active/inactive connections to the RDG server at any given moment.
Failed Connection AuthorizationShows the total number of requests that failed due to insufficient connection authorization privilege.
Failed connectionsShows the number of connection requests that are all failed due to errors and authorization failure
Failed Resource AuthorizationShows the total number of requests that failed due to insufficient resource authorization privilege.
Successful connectionsShows the number of requests that were successfully processed and connected

Events: RD Gateway Server Connection Errors

Log: System

Source: Microsoft-Windows-TerminalServices-Gateway

Event IDs: 201,203,204,301,305,306,308,311,1001

Event Logs taken from RD Gateway Server Connections | Microsoft Docs