If a user is having problems being authenticated over PPP, a PPP.log file can be created to provide debugging information.
Value: 1 standard logging
Value: 2 verbose logging
Another handy tool is the Dial-Up Networking Monitor, which is launched at the dial-up client and shows the status of a session that's in progress. This tool will report information about the amount of data transmitted and received and the number of errors encountered in transfer. It can also show which lines are being used for multi-link transmission.