Quick tip for anyone working from a Starbucks on a work laptop that's "protected" by Sophos or any other software that intercepts web modals. After connecting to the official public WiFi network, normally the computer will open up the modal displaying a "You're Connected" message and some advertising; in my case Sophos was blocking this modal (and annoyingly giving no indication any window had been blocked). A great option for situations like this is to visit 1.1.1.1 or 0.0.0.0 in your browser, which will often manually trigger this modal process. However, at least at my local green mermaid mansion, this still doesn't work. After several extended forum searches (on my phone) I finally found the magic address, which I am publishing here both for you and for myself next time I'm inevitably locked out for my own good:
Try to connect to the Starbucks WiFi and then visit http://captive.apple.com/hotspot-detect.html