The issue was due to a bug in a code within Private Agent management services. We were able to stabilize Private Agents overnight and will be applying code fixes today that should resolve the problem permanently.

Top 20 Synthetic Monitoring Tools
Synthetic monitoring allows teams to monitor and measure website and web application performance around the clock from every conceivable vantage point, and to receive alerts before issues begin to impact real users. Here are our top picks for synthetic monitoring tools, leading with our own at Dotcom-Monitor.