Thank you so much for this! It was the only suggestion on this thread that worked for me. I reset network settings a few times. Forgot networks and tried to log in again to no avail.
I even contacted Apple Support with disastrous results. They had me run through the same steps despite me telling them I already did myself. The agent even had me reset network settings while on the phone with him which of course disconnected me from the call. He never called me back despite asking for a callback number in the event we get disconnected.
So I complained via Twitter which usually gets me a quick response from most companies. They asked me a bunch of repetitive questions and I reiterated that this problem is with ALL public unsecured networks and the log in page no longer loads on Safari. I even listed all of the places I’ve gone to where it won’t connect (Starbucks, Coffee Bean, Target, a couple of malls, etc). They determined that the problem lies with all the individual networks I was trying to access and that I needed to contact all of them. Really??? Even after I insisted this was working fine on iOS 11 public beta and stopped working after I updated to the official iOS 11 and this it is too much of a coincidence that all of these networks decided to stop working at the same time, they stopped responding to me.
So aggravating that you get stupid solutions from their support staff.