Removing the restricted-extras will not help you with a wifi issue. The software-properties package will not make the system/wifi unstable.
You added software-properties to get the latest version of Audacious, did you install that using the PPA? As we don't know what the PPA pulls in during installation that might well have caused it. Please tell us more about the things you did when the connection issue started. I suggest to open a new topic for this wifi issue so you get the best help with that.