PPPOE Logging

Hey Everyone, 

We run our Fortigates behind bridged VDSL2 modems running the PPPOE Authentication.

We are having issues with one site where the carrier is saying there is a loss of sync but I'm not sure how I can view logs for this retroactively. The modem iteself is showing sync but the logging is limited on the device for pppoe pass through.

Is there a way to have a fortigate unit verbose log the PPPOE service without being connected via SSH/CLI?

Thanks