Fix Magento 2 Cron Failure

My Magento 2 store sits on a dedicated server and, after I tweaked the cron-job settings at OS level, all scheduled tasks stopped running. The site itself loads, but orders are not invoicing, catalog rules never refresh, and the crontab log is silent. I need someone to:

• locate the root cause of the failed Magento 2 cron (whether it’s pathing, permissions, PHP binary mismatch, or something deeper in the crontab)
• restore the three default Magento cron tasks so they execute on schedule and appear as “success” in `cron_schedule`
• provide a short recap of what was wrong and the exact commands or config lines you changed

SSH access, Magento CLI, and root privileges are ready for you. A fix is considered complete when the cron jobs run for at least two consecutive cycles without errors and after 48 hours and I can see order emails, sitemap generation, and indexers updating automatically along with products.