EC2 not responding? The issue might be here (and it seems too basic to happen)

In day-to-day cloud operations, some incidents stand out not because of their complexity, but quite the opposite. They are those cases where, once you discover the root cause, you think: “this can’t be it”. This is one of them. ⸻ The scenario The EC2 instance was running, with a public IP and everything seemingly correct. Status: running Public IP available No visible alerts Even so, every attempt to access it resulted in a timeout. No clear error. No direct clue. ⸻ Where to look first In situat