How the checks work
Every five minutes a scheduled job on a VPSLake server sends one ordinary web request to each service, all at the same time. It records whether an answer came back, the HTTP status code and how long the answer took, then keeps seven days of results.
The job requests one fixed public page per service. It never logs in, makes a payment, or opens the mobile app, so it tells you whether the public front door is open, not whether every feature behind it works.