Hey @sandyy !
Welcome! Great question!
A great place to start would be to study/learn about our connection monitor here. This goes into some depth of how we monitor, maintain, and ultimately mark a WAN connection as healthy or unhealthy.
The health of that port will be reported on the dashboard or via email alerts (Network-wide -> Alerts -> Uplink Status changes) or via API with a GET on /organizations/{organizationId}/devices/uplinksLossAndLatency. (API Documentation)
Hope that helps!
-Cheers!