On-Demand Hotspot

I use Xfinity On Demand Hotspot to access WiFi and have never had an issue (using a Mac). These past few days, I am unable to connect to the hotspot “xfinitywifi” despite it being available with all bars for Good connectivity.

In my Mac WiFi settings it says “WiFi has the self assigned IP address and will not be able to connect to the internet.”

The only thing I've found online that I haven't tried is rebooting the router, but I'm using On Demand I don't have the router.

Any ideas? Help!