Since you mentioned using 15.0 on a iMac you may have the firewall on OS blocking Firefox. See https://support.mozilla.org/en-US/kb/firefox-blocked-macos-15-sequoia-firewall-what-you I moved this thread from Firefox for iOS (for iPhone/iPad) to Firefox section as you mentioned iMac which uses '''macOS'''. iOS is the mobile OS used on iPhones and early iPads as current iPads uses the similar iPadOS.