Internet troubleshooter
Choose what you notice. If you have saved a speed test in this browser, the checklist uses those numbers. It will not claim a router or modem has failed.
How this measurement works
Rules are fixed: for example, usable download with a large latency increase under load points to queueing, not to a dead radio. Each step includes why it might help, how to retest, what you should see, and a confidence level.