On a fresh installed kubuntu 18.04, i cannot login properly to a public wifi that worked just fine with 16.04, and still works for other users around me on various hardware/os.
When i connect, I am redirected as expected to the public network authentication web page just fine.
I can then authenticate with credentials, but the problem starts there: the authentication doesn't stick, and i get an error after the login page redirects me (503, Http/1.1 Service Unavailable).
If i try to open another page, i still get redirected to public network login page, but keeps failing.
I looked up a bit for solution, but the issues i could find are more related to displaying the login page, which works just fine for me.