Wifi - works until you need it

So you get stuck in Continental's partner lounge at the newly deserted T4, which appears to be primarily KLM. "do you have Wifi?" 

"Sure. Here's the details"

Computer finds network, but it can't get a website outside, so there's obviously a problem. I can see other networks from BT Openzone and T-Mobile. I try the BT one, Takes my money, slow as fuck. I try the T-Mobile one and it charges me money, but at least it works. A further example that WiFi hotspots work just great right up to the point that you need them.