Related: browser is confused and caches some of the captive portal content for the site you want to visit, so it remains broken even after the portal lets you t

Related: browser is confused and caches some of the captive portal content for the site you want to visit, so it remains broken even after the portal lets you through. Add a cache-buster to the end of the URL -- ?a=1 for example -- and most webservers will handle the modified URL without complaints.