Wi-Fi connected but no internet

A connection to the router does not prove that the internet connection is working.

Do not factory-reset a router speculatively or indiscriminately disable Wi-Fi security or a firewall. Get permission before changing someone else’s network.

Open a familiar website on a second device on the same Wi-Fi. Temporarily turn off its mobile data for this test.
If every device fails, follow the router guide. If the second device works, restart only the affected device.
For hotel or guest Wi-Fi, open the browser and check for a sign-in page. Use only the expected network and never bypass certificate warnings.
Check whether device access rules or parental controls block access. Ask the connection owner before changing settings; do not disable the firewall indiscriminately.

Test after each step and stop when the issue is solved. Checkmarks are not permanently saved.