My production-ready MERN application has started throwing a mix of back-end problems that now block core business flows. The Node/Express layer crashes under load, several REST endpoints return inconsistent data or time out, and MongoDB connections drop unexpectedly. On top of that, both payment gateways—Stripe and Ziina—fail at random points in the checkout, leaving orders in an indeterminate state. The Admin panel, also React-based, shows stale or missing data whenever these glitches occur. I need you to: • Trace and eliminate the server crashes, API failures, and data-processing bottlenecks. • Restore stable, persistent database connectivity. • Debug and stabilise the Stripe and Ziina payment workflows end-to-end. • Ensure the Admin panel reflects real-time, accurate information once the fixes are in place. Acceptance is simple: no uncaught exceptions in logs, all endpoints return expected payloads under load, payments settle successfully every time, and the Admin panel mirrors live data without lag. I’ll spin up staging so you can push branches for review and automated testing. If you live and breathe MongoDB, Express, React, Node, and have hands-on experience with Stripe (Ziina is a plus), I’m ready to share the repo and dive straight in.