# IT Troubleshooting Knowledge Base

- [IT Troubleshooting Knowledge Base: Your IT Support Hub](https://docs.derekdinh.com/introduction.md): A central IT support hub covering networking, Windows, macOS, Linux, hardware, security, and cloud/SaaS for helpdesk teams, sysadmins, and power users.
- [How to Use the IT Troubleshooting Knowledge Base Well](https://docs.derekdinh.com/how-to-use.md): Navigate the knowledge base, interpret guide structures, use search effectively, and apply troubleshooting steps safely to resolve IT issues faster.
- [Contributing Troubleshooting Guides to the Knowledge Base](https://docs.derekdinh.com/contributing.md): Submit new guides or improvements using the standard template, style conventions, and review process to keep the knowledge base consistent and actionable.
- [Troubleshooting No Internet Connection on Windows and Mac](https://docs.derekdinh.com/networking/no-internet-connection.md): Follow these step-by-step instructions to diagnose and resolve a complete loss of internet connectivity on Windows and macOS systems.
- [Diagnosing and Fixing Slow Network Speeds on Your Device](https://docs.derekdinh.com/networking/slow-network.md): Step-by-step guidance to identify what is consuming your bandwidth and restore normal network speeds on Windows and macOS devices.
- [Resolving DNS Failures and Name Resolution Errors Quickly](https://docs.derekdinh.com/networking/dns-issues.md): Learn to identify DNS failure symptoms, flush your DNS cache, switch to a reliable DNS server, and verify resolution using nslookup across all platforms.
- [Fixing VPN Connection and Authentication Failures Fast](https://docs.derekdinh.com/networking/vpn-connectivity.md): Diagnose and resolve common VPN errors including authentication failures, connection timeouts, and split tunneling issues on Windows and macOS.
- [Step-by-Step Wi-Fi Troubleshooting for Common Issues](https://docs.derekdinh.com/networking/wifi-troubleshooting.md): Resolve Wi-Fi connection failures, poor speeds, and DHCP errors by following this structured guide covering drivers, bands, interference, and TCP/IP reset.
- [Troubleshooting Windows Boot Issues (Complete Guide)](https://docs.derekdinh.com/windows/boot-issues.md): Diagnose and fix Windows PCs that won't power on or get stuck at the boot screen, from checking cables to repairing the MBR and beyond.
- [Troubleshooting Windows Blue Screen of Death (BSOD)](https://docs.derekdinh.com/windows/blue-screen-errors.md): Read stop codes, analyze minidump files, and resolve the most common Windows Blue Screen of Death errors with drivers, disk checks, and system file repair.
- [Diagnosing and Resolving Windows Performance Issues](https://docs.derekdinh.com/windows/performance-issues.md): Spot CPU, RAM, and disk bottlenecks in Task Manager, trim startup bloat, run Disk Cleanup, scan for malware, and tune power settings for peak performance.
- [Resolving Windows Update Failures and Common Error Codes](https://docs.derekdinh.com/windows/update-failures.md): Decode Windows Update error codes, clear corrupted caches, repair the component store with DISM, and manually install updates from the Update Catalog.
- [Diagnosing and Resolving Windows Device Driver Problems](https://docs.derekdinh.com/windows/driver-problems.md): Spot driver issues in Device Manager, update or roll back drivers, reinstall problem devices, and use Driver Verifier to isolate the source of instability.
- [Troubleshoot macOS Startup Failures and Boot Loops](https://docs.derekdinh.com/unix/macos-startup-issues.md): Diagnose and fix Mac startup failures including spinning beach balls, stuck Apple logos, and boot loops using built-in macOS recovery tools.
- [Linux Boot Repair: GRUB Errors and Filesystem Issues](https://docs.derekdinh.com/unix/linux-boot-repair.md): Fix Linux systems that fail to boot due to GRUB errors, corrupted filesystems, or bad kernel parameters using recovery mode and command-line tools.
- [Resolving File Permission Errors on Linux and macOS](https://docs.derekdinh.com/unix/permission-errors.md): Understand and repair Linux and macOS file permission errors using chmod, chown, and sudo, covering web servers, SSH keys, and home directories.
- [Resolving Disk Full Errors on Linux and macOS Systems](https://docs.derekdinh.com/unix/disk-full.md): Identify and reclaim disk space on Linux and macOS using df, du, find, package cache cleanup, log management, and the macOS Storage Management tool.
- [Troubleshooting a PC That Produces No Display Signal](https://docs.derekdinh.com/hardware/no-display.md): Diagnose and fix a PC that powers on but shows no video: check cables, input sources, RAM, GPU seating, integrated graphics, and BIOS beep codes.
- [How to Diagnose and Resolve PC Overheating Problems](https://docs.derekdinh.com/hardware/overheating.md): Identify thermal throttling and shutdown symptoms, then resolve overheating by cleaning dust, reapplying thermal paste, and tuning BIOS fan curves.
- [Identifying and Responding to Storage Drive Failure](https://docs.derekdinh.com/hardware/storage-failure.md): Spot early warning signs of a failing drive, run SMART diagnostics with CrystalDiskInfo or smartctl, back up data, and know when to replace the drive.
- [Fixing Peripherals That Are Not Detected by Your PC](https://docs.derekdinh.com/hardware/peripheral-not-detected.md): Resolve USB devices not recognised, missing printers, and Bluetooth pairing failures using Device Manager, driver reinstalls, and firmware updates.
- [Troubleshooting Outlook Not Opening, Crashing, or Slow](https://docs.derekdinh.com/email/outlook-issues.md): Resolve Outlook crashes, profile corruption, and OST/PST file errors with these step-by-step diagnostic and repair procedures for Windows.
- [Troubleshooting Email Not Sending or Stuck in Outbox](https://docs.derekdinh.com/email/email-not-sending.md): Fix emails stuck in Outbox by verifying SMTP settings, testing connectivity, checking size limits, and validating sender authentication.
- [Troubleshooting Calendar Not Syncing in Outlook or Mobile](https://docs.derekdinh.com/email/calendar-sync.md): Resolve calendar sync failures in Outlook and on mobile by checking Exchange connectivity, permissions, and account configuration step by step.
- [Troubleshooting Microsoft Teams Loading and Meeting Issues](https://docs.derekdinh.com/email/microsoft-teams-issues.md): Fix Teams stuck on the loading screen, audio/video problems, sign-in loops, and network blocks with these step-by-step troubleshooting procedures.
- [Malware Removal: Detection, Cleanup, and Hardening](https://docs.derekdinh.com/security/malware-removal.md): Identify malware symptoms, isolate infected systems, run targeted removal scans, and apply post-cleanup hardening steps to prevent reinfection.
- [Active Directory Account Lockout: Diagnose and Fix](https://docs.derekdinh.com/security/account-lockout.md): Unlock Active Directory accounts, trace the lockout source using Event Viewer, and eliminate stale credentials causing repeated lockouts.
- [MFA Troubleshooting: Codes, Lost Devices, and Resets](https://docs.derekdinh.com/security/mfa-issues.md): Fix MFA code failures caused by time sync, recover access after losing your device, and reset MFA in Microsoft 365 and Google Workspace.
- [Phishing Response: How to Identify, Contain and Report](https://docs.derekdinh.com/security/phishing-response.md): Identify phishing emails, contain damage after clicking a malicious link, report threats in Outlook and Gmail, and complete the post-incident checklist.
- [Troubleshooting Microsoft 365 Sign-In and Activation](https://docs.derekdinh.com/cloud/microsoft-365-issues.md): Resolve common Microsoft 365 problems including sign-in failures, licensing errors, activation issues, and Outlook connectivity problems.
- [Troubleshooting Google Workspace Sign-In and Drive](https://docs.derekdinh.com/cloud/google-workspace-issues.md): Fix Google Workspace sign-in failures, Drive sync issues, Meet audio/video problems, Gmail loading errors, and verify service health status.
- [Troubleshooting OneDrive Sync Errors and Reset Steps](https://docs.derekdinh.com/cloud/onedrive-sync.md): Resolve OneDrive stuck sync, error codes 0x8007016A and 0x80070194, path length limits, account relinking, and full reset procedures.
- [Troubleshooting Azure AD and Entra ID Sign-In Issues](https://docs.derekdinh.com/cloud/azure-ad-sign-in.md): Diagnose Azure AD and Entra ID sign-in errors including AADSTS codes, conditional access blocks, device join status, and re-join procedures.
- [Common IT Error Codes and Windows Update Reference](https://docs.derekdinh.com/reference/common-error-codes.md): A comprehensive reference of Windows system, update, Microsoft 365, Azure AD, OneDrive, and network error codes with recommended actions.
- [IT Diagnostic Commands Reference for Windows and Mac](https://docs.derekdinh.com/reference/diagnostic-commands.md): Essential IT diagnostic commands for network troubleshooting, disk health, system info, and OS-specific tools on Windows, macOS, and Linux.
- [Common Network Ports Reference Guide for IT Support](https://docs.derekdinh.com/reference/network-ports.md): A complete reference of TCP and UDP ports IT staff need to know, covering email, web, remote access, directory services, file sharing, and VPN.
- [IT Troubleshooting Knowledge Base Glossary of Terms](https://docs.derekdinh.com/reference/glossary.md): Definitions of 40+ common IT terms used throughout this knowledge base, from BSOD and BIOS to VPN, VLAN, RAID, and Zero-Trust security concepts.