Have you tried using the FoxyProxy standard add-on. I know that is what I would do if I needed to use a socks5 connection on Firefox, however I have not tried this in a while. Here is a link to the IP Vanish VPN website that demonstrates how to configure FOXYPROXY to add a Socks5 connection.
How to use FoxyProxy to add a socks5 connection
Good luck.
In the future, please add more information next time in your questions, as a very vague question that you asked above: " why is my socks5 connection not working? " Is very hard to diagnose without more information about your browser, computer, settings of your computer and browser, and a little information on the Socks5 connection you are trying to use.
Have you tried using the FoxyProxy standard add-on. I know that is what I would do if I needed to use a socks5 connection on Firefox, however I have not tried this in a while. Here is a link to the IP Vanish VPN website that demonstrates how to configure FOXYPROXY to add a Socks5 connection.
[https://support.ipvanish.com/hc/en-us/articles/360001410573-How-to-Configure-the-SOCKS5-Proxy-in-Firefox-#:~:text=How%20to%20Configure%20the%20SOCKS5%20Proxy%20in%20Firefox%3F,Standard%20add-on%20to%20your%20browser.%20More%20items...%20 How to use FoxyProxy to add a socks5 connection ]
Good luck.
In the future, please add more information next time in your questions, as a very vague question that you asked above: " why is my socks5 connection not working? " Is very hard to diagnose without more information about your browser, computer, settings of your computer and browser, and a little information on the Socks5 connection you are trying to use.