I installed SmartProxy 0.9.7.1 on Firefox 84 & Windows 10 20H and added an proxy server as 127.0.01:8100 (Goflyway local proxy port), it was unable to access google.com, facebook.com through SmartProxy. But when this add-on runs normal on web browsers like Chrome/Edge, everything is fine. I don't know what's wrong. So sorry for the star rating...