If someone is simply connected to your Wi-Fi as a guest/user, their visibility is actually quite limited compared to the .

If your computer has "File and Printer Sharing" turned on, they might be able to see and access folders you’ve marked as shared. How to get them off your network

A VPN creates an encrypted "tunnel" for your data. Even if they own the router, they will only see that you are connected to a VPN—all other traffic will be invisible.

How to Hide Your Internet History from WiFi Owners - Top10VPN

Often, people leave their router's admin login as "admin/admin." Change this so the neighbor cannot log into your router settings to find your new Wi-Fi password.

If you suspect a neighbor is piggybacking on your connection, follow these steps to secure your router:

If you are the one connected to their Wi-Fi and are worried about them spying on you: