The WiFi nest box camera relies on your home WiFi. The 15 meters distance is the test result from an open area with straight sight. The wall or tree could block the WiFi signal seriously.
You will have to make sure the WiFi signal is good enough to stream the high-definition video. Otherwise, you can add the PLC adaptor to extend the WiFi signal around the birdhouse.
Please follow the instruction below to test the WiFi signal with your mobile phone.
1.Firstly, grab your mobile phone and go to the place where you plan to install bird box.
2. Next go to WiFi setting of your mobile phone.

3. Now, check the signal bar, it should always stay on strong condition or close to the strong condition. You also can slide the tab back on to show the green ON position to allow a new search. If the signal is strong, you are good to install WiFi bird box camera.

It is important to know the camera only works with 2.4Ghz WiFi. If what you have is a dual-band router that has combines 2.4Ghz and 5Ghz into single WiFi, you will need to log in to your router and give an independent name to 2.4Ghz WiFi, otherwise, the WiFi camera will not work with your dual-band router.
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Hook up birdhouse camera to WiFi
Thank you so much. I will place the order, as I will put it closer to the house if need be.
Thanks
Dennis