I'm having an issue with Firefox and MAC OS X El Capitan. Whenever I load a page, I lose my internet connection when the website has linked files larger than 23 kb in local test sites. - Firefox Version: 43.0.4 - Operating System: OSX El Capitán version 10.11.2 - The pages are hosted on a local server (MAMP). It is a very strange problem. Every time I download a page, if a file has more than 23 kb approximately (either css, jpg, png or js) I lose the internet connection. I've looked into the console.app and there aren't any error logs registered. To get to this error I've tried other browsers, and other operating systems, even with the same browser on Mac OS X 10.6 and there is no problem (in pages hosted on MAMP) These are the tests I did where the problem disappears: - The same page on a remote server works fine. - I tested with other operating systems (Windows 10, Vista, MAC OS X 10.6) and there was no problem. These are the tests I did where the problem persists: - I turned off the firewall and antivirus, and the error continues. - I've uninstalled and installed Firefox deleting all files and the error appears again. - I installed the version for developers and I have the same problem again. To verify the cause of this issue, I started a website from scratch. When I inserted a file of more than 23 kb (either a jpg, css or js), after reloading the page, I immediately lost the internet connection. On the contrary, the same website on a local server and with other browsers does not have the error. Only with Firefox. Finally, if the pages do not contain any file that exceeds the 23 kb or if they are hosted on a remote server the page loads correctly. As I said before it is very strange. I'd appreciate any help from somebody familiar with this issue. Thank you so much.