Doc: Diagnose Network Issues with `curl`

[Juju-archy]

Checking for existing issue

• I have checked for existing issues

Describe the content you'd like to see

Diagnose Network Issues with curl to Troubleshooting Guide

Use Case

Including this in the troubleshooting guide would:

• Help users quickly identify if issues are related to the network or the application itself.
• Improve the efficiency of diagnosing and resolving connectivity problems.

Description

It would be helpful to include the following curl command in the troubleshooting guide. This command can diagnose network-related issues by providing detailed timing information for each step of the connection process (DNS resolution, network latency, TLS handshake, server response).

Command

curl -o /dev/null -s -w "DNS resolution: %{time_namelookup}s\nTCP connection: %{time_connect}s\nTLS handshake: %{time_appconnect}s\nTime to first byte: %{time_starttransfer}s\nTotal time: %{time_total}s\n" https://example.com

[Kirbeerus]

@Juju-archy Can you look into doing a PR about this issue ?