In response to the question from tech support:

When I try to access the Lewisville Library web site it goes through the usual “ASSOCIATING” etc message until this:

After a wait, the message under “Wireless Status changes to “Connection Prohibited” and all three Status windows go blank.

If I connect directly to the AP I get a message from the browser saying that this system (1.1.1.1) is untrusted and gives me the option to continue.  This is what I’ve done until now.  I can’t show a screen shot because once you’ve done this the browser “remembers” and won’t show this message again.  Then I get this screen:

Now when I close this screen I select any web site and I get (when I’m in Safari, Firefox tells me to “get out of there”…):

Press continue and this screen comes up:

Once I press “Accept” I am on the internet.

== John