cant visit 127.0.0.1 after changing proxy on JOKER machine.

As per writeups, i am trying to change the proxy and visit 127.0.0.1 but nothing happens. I am currently using foxyproxy to quickly add proxies. I named a new proxy as squid and added 10.10.10.21 as ip address and 3128 as port to use the squid proxy avilable on JOKER. I did this manually from network prefrences in my firefox browser on kali linux. Nothing happens.
Also trying to scan the udp ports on this machine takes forever.

were you able to visit 127.0.0.1 eventually?? i am stuck

I’ve no idea what might be going on here but some things to consider:

Have you configured the proxy to proxy 127.0.0.1 traffic?
Have you configured the browser to go to the proxy for 127.0.0.1 sites?
If you want 127.0.0.1 to point to 10.10.10.21 I am not sure the proxy will do that but I don’t know what the write ups are telling you to do.