Why do you always doubt me?
It connected once to connectivity-test.ext.nokia.com (still redirected to my own server) and never again, even though I have left and returned home many times since then.
~ # exec /usr/bin/socat -v TCP-LISTEN:80,bind=0.0.0.0,reuseaddr,f ork SYSTEM:'echo HTTP/1.1 204 No Content' < 2016/01/15 19:09:53.762146 length=24 from=0 to=23 HTTP/1.1 204 No Content > 2016/01/15 19:09:53.763488 length=122 from=0 to=121 GET / HTTP/1.1\r User-Agent: \r X-Nokia-WLAN-Connectivity-Test: true\r Host: connectivity-test.ext.nokia.com\r Accept: */*\r \r