This is due to the "https" secured protocol.
When connected to an open public WiFi network, just open Morph browser and open this website: http://neverssl.com
You will be directly rerouted to the web page of the web provider to activate your connection.
Tip: You can create a webapp with Webber with this website that you can rename "Public WiFi" and just click on it after you did connect to the WiFi. Just ensure you activate the "URL" bar when you create the webapp....