Even the hotel wifi keeps popping up advertisements.

WIFI in public areas may reveal personal information, so it is recommended to disconnect it immediately.

Because criminals get the password of public WIFI, they will provide all guests with a network connection very similar to the original WiFi, and redirect the network traffic of all devices through black devices. It is not surprising that criminals use software to obtain Mac address, login history and device owner's name, and get what users are doing and what software they are using at the moment, so they will advertise.