Hi,
The currency won't change if the user session doesn't change.
The geolocation plugin will only set the currency in the user session when the customer arrives on the website the first time a page is requested.
After that, even if you change your IP address, if the user session already has the currency set in the session of the user, it won't change it.
So when you test, you need to either use another browser when you switch your IP, or clear your user session, or use the anonymous mode of your browser.
SSL is not required.