When using a public Wi-Fi you may need to use a login page and enter some access credentials to get online. The login page is presented when the local Access Point intercepts a web page request, and substitutes its own login page instead. Sometimes the login page does not appear, due to a diabolical problem with Domain Name Server DNS (internet telephone number) lookups. DNS lookups may also be blocked, so you can't get anywhere.
Launch a browser and enter this easy to remember all-numeric IP address:
1.1.1.1 and press return.
If you get the local network login page, enter your credentials and proceed.
If you get the CloudFlare** splash page, your internet is working, but DNS lookup may not be working.
**CloudFlare is NOT part of the solution, they just own the easiest to remember all-numeric IP Address.