[FrankPetrilli]

Sounds like something GCP support would love to help you troubleshoot. The disruptions I'm aware of have no correlation to load balancer traffic paths.

What's the actual reason listed for the 502s in Stackdriver? That's a great first step.

[broth]

All Stackdriver logs for the load balancer have the following for each request as the status details: failed_to_connect_to_backend

We've tried the following with no luck: - Restarted GCE instances in backend service - Recreated the backend service - Recreated the HTTPS load balancer - Switched the balancing mode of the backend service to rate instead of utilization since monitoring was stating the backend service CPU utilization was 500% (another red flag)

We are, however, able to directly connect to the GCE instances within the backend service via external IP.

Have not heard much back from Google support.

[broth]

Update

This ended up being due to SNI getting enabled on our HTTPS binding in IIS when using a Let's Encrypt cert. Apparently, the GCP HTTPS LB does not like SNI.

[gcardone_]

SNI is supported by GCP load balancers, see https://cloud.google.com/load-balancing/docs/ssl-certificate...