1. Google Search Console
2. Broken Link Checkers (Online Tools)
3. Browser Extensions (e.g., Check My Links)
4. Crawling Software (e.g., Screaming Frog SEO Spider)
5. Backlink Analysis Tools (e.g., Ahrefs)
6. Website Audit Tools (e.g., SEMrush)
7. WordPress Plugins (e.g., Broken Link Checker for WordPress)
8. Manual Website Audit
9. Third-party Monitoring Services
10. Checking Web Server Logs

Here are few reasons 1- poor user experience 2- Unclear preposition 3- Unclear call to action 4- Irrelevant content 5- Complex checkout

More over if you need help. I am an SEO expert. You can contact me.

Choose relevant content and websites/ forums Link pages as well not just home page Try different types of Backlinks