When there is a problem with a pod federation, you can troubleshoot using the Cloud Pod Architecture (CPA) alerts.

When any pod in a pod federation goes down, a "Failed to communicate with target pod" alert appears for other pods in the federation. Clicking on this alert (which can be found by searching for the alert from the Alerts tab) shows which connection to a target pod is affected. Note that when connectivity is reestablished, the alert status changes from Active to Inactive.