Educational reference. Follow your organization's IT, security and change-control policies. Only troubleshoot systems you are authorized to access. In clinical, lab or industrial settings, follow your facility's procedures before touching connected equipment.
Order follows a physical → local config → network → service → escalate flow. Commands are built into Windows; each links to its Microsoft Learn reference. macOS and ChromeOS steps link to Apple and Google support pages. Replace placeholders like <default gateway> with real values.
Checklists by symptom
No internet · Wi-Fi drops · Can't print · Can't log in · Slow computer · Email not syncing