Network Basics: Troubleshooting SaaS Application Connectivity on AWS

00:00 Setup & Baseline Check 02:34 Internet Layer Troubleshooting 06:20 Transport Layer Troubleshooting 11:19 Application Layer Troubleshooting 13:10 Recap & Wrap-up Troubleshooting SaaS application timeout error Using TCP/IP Layers (AWS) A SaaS app goes down at 2AM with 504 Gateway Timeout errors, and this video shows a simple TCP/IP-layer mental model to troubleshoot without a network specialist. Using an NGINX reverse proxy in a public subnet and a Flask API in a private subnet, the walkthrough debugs from the internet layer to transport and then application: it finds a wrong backend IP in NGINX, fixes a blocked TCP/5000 security group rule, and finally resolves an app-layer hang by checking logs and removing a simulated fault file. Along the way it demonstrates the key tools—curl, NGINX logs, ping, traceroute (TCP SYN), ncat, ss, and journalctl—and how the same 504 can mask different root causes across layers. 🌐 Training & mentorship: https://www.opsaccelconsulting.com 📩 info@opsaccelconsulting.com #DevOps #AWS #GCP #Linux #CloudSecurity #Troubleshooting