https://thedavidpage.pages.dev/tags/troubleshooting/Recent content in Troubleshooting on The David PageHugo -- gohugo.ioenSun, 02 Aug 2026 09:00:00 +0700https://thedavidpage.pages.dev/posts/cloud/azure/front-door/waf-policy-arm-resource-id-formatting-error/Sun, 02 Aug 2026 09:00:00 +0700https://thedavidpage.pages.dev/posts/cloud/azure/front-door/waf-policy-arm-resource-id-formatting-error/<p><strong><code>Policy ArmResourceId has incorrect formatting</code> — an Azure CLI error message that cost me a whole debugging session, when the real reason was just a hyphen in the policy name.</strong></p> <p>Hi everyone 👋</p> <p>Setting up an Azure Front Door WAF Policy through the CLI, I ran into an error that — as it turns out — a lot of other people have been hitting for over three years, ever since it was first reported back in December 2022.</p>https://thedavidpage.pages.dev/posts/cloud/aws/networking/mtu-9001-path-mtu-discovery-black-hole/Fri, 20 Feb 2026 09:00:00 +0700https://thedavidpage.pages.dev/posts/cloud/aws/networking/mtu-9001-path-mtu-discovery-black-hole/<p><strong>Ping works. SSH works. But the moment the app sends a large payload over VPN or cross-region peering, it just&hellip; hangs. This is why.</strong></p> <p>Hi everyone 👋</p> <p>This is a classic debugging trap that can burn a new DevOps engineer several days, precisely because the system never throws a clear error log.</p> <h2 id="-the-confusing-symptom">😱 The confusing symptom</h2> <p>Two EC2 instances in different VPCs, connected over VPC peering, VPN, or Direct Connect. Ping between them responds fine. SSH works fine too. But the moment the application transfers a large file, or sends a long JSON payload over an API call on that same connection, the request hangs indefinitely until it eventually times out.</p>