If you cannot get to the login page of the capitive portal, try to access a non-ssl site like http://neverssl.com

This is because captive portals typically intercept any HTTP requests made by users and redirect them to a login page. However, HTTPS requests are not intercepted in the same way, as the SSL handshake prevents the captive portal from intercepting the traffic and presenting the login page.

By visiting a non-SSL (HTTP) page initially, the captive portal can intercept the request and redirect to the login page, allowing you to authenticate and gain access to the network.