Frequently Asked Questions

SubLearn works best on modern browsers: Chrome 90+, Firefox 88+, Safari 14+, and Edge 90+. We recommend using the latest browser version for best performance, security, and feature support. Internet Explorer is not supported. Mobile browsers (Chrome, Safari, Firefox) are fully supported on iOS 14+ and Android 8+.

Absolutely! SubLearn is fully responsive and optimized for phones and tablets. All features work on mobile: video playback, interactive subtitles, exercises, flashcards, and AI conversations. We recommend screen sizes 320px+ (iPhone SE and up). For the best mobile experience, add SubLearn to your home screen for app-like experience (PWA support).

Video loading issues are usually caused by slow internet, browser cache, or firewall restrictions. Try: refreshing the page, clearing browser cache (Ctrl+Shift+Delete), checking your internet speed (need 5+ Mbps for HD), disabling VPN/proxy, or trying a different browser. If issues persist, contact support with video ID and error message.

For audio issues: check volume settings (browser + system), ensure audio isn't muted in video player, try different headphones/speakers, update audio drivers, disable browser extensions (especially ad blockers), and test in incognito mode. If audio works elsewhere but not on SubLearn, check browser's site permissions for audio.

Progress syncs automatically every 30 seconds when online. Sync issues occur if you're offline, have unstable connection, or browser blocking cookies. Try: refreshing the page, checking internet connection, enabling cookies for sublearn.org, logging out and back in. Your progress is saved locally and will sync when connection is restored.

Chrome/Edge: Ctrl+Shift+Delete → Time Range: All time → Check "Cached images and files" → Clear data. Firefox: Ctrl+Shift+Delete → Time Range: Everything → Check "Cache" → OK. Safari: Safari menu → Preferences → Privacy → Manage Website Data → Remove All. After clearing cache, refresh SubLearn and log back in.

Performance issues can be caused by: too many browser tabs (close unused ones), outdated browser (update to latest), low device RAM (close other apps), slow internet (check speed), or browser extensions (disable ad blockers). Enable Performance Mode in Settings to reduce animations and optimize loading. Restart your browser after applying changes.

401 Unauthorized: Log in again. 403 Forbidden: Access restricted (subscription required). 404 Not Found: Content deleted or URL wrong. 500 Server Error: Our servers are down (retry in a few minutes). 503 Service Unavailable: Maintenance in progress. Check status.sublearn.org for live server status and scheduled maintenance.