If you make a change that causes problems, click the recycle arrow icon next to any preference to reset it to default. Write down any changes you make so you can revert them later.
Click the tab. Look for red error messages. Messages about CORS (Cross-Origin Resource Sharing), CSP (Content Security Policy), or mixed content can indicate why the site is blocked.
If Firefox is configured to use a proxy that blocks certain sites: how to unblock a site in firefox
If you are on a (like school, work, or public Wi-Fi).
Navigate to C:\Windows\System32\drivers\etc\hosts . Open with Notepad as Administrator. If you make a change that causes problems,
This routes your website requests through an encrypted tunnel, hiding them from local DNS filters and unblocking restricted sites. 7. Use a Virtual Private Network (VPN)
: Built-in features like Enhanced Tracking Protection (ETP) or certificate warnings block content that seems unsafe or malicious. Look for red error messages
Whitelist the specific URL within that extension's settings. 5. Change Network and Proxy Settings