In general, changing settings on a router can be visible to the owner or administrator of the network. When you make changes to the router settings, it often reflects in the router's configuration interface or management console. However, whether the owner actively monitors these changes depends on their level of involvement and the logging capabilities of the router.
If you're making changes on your own device connected to the Wi-Fi network (e.g., changing your device's DNS settings), that typically wouldn't be directly visible to the router owner, but they might notice changes in overall network behavior.
Always ensure you have permission to make changes to the router settings, as unauthorized modifications can lead to network issues or breach of terms of service.
