Hello @Dimak 

it's good step to check the camera signal strength, it is aslo recommended to checkif router has any advanced wireless settings that may affect the camera stability as FAQ here.

 What should I do if my Tapo smart camera keeps losing connection or going Offline?

For camera unstable problem, can you help provide some information here, and we may need to get  the case escalated for further analysis. 

1Led status on a smart device when it is offline: Red/ Flashing Green/ Solid Green etc.

2. MAC address of the Camera ( please share via Private message)

3. When the issue occurs, does the smart device work in the local network?

For a test, connect your mobile device to the home Wi-Fi network at that time and see if the Tapo device is still accessible in the local network?

4. the model number Wi-Fi router and your network topology:

e.g. ISP Spectrum-Archer C7 router<Wireless> tapo device

5. How often does the issue happen, and how does the recover the connection, like reboot the camera or reboot the router?

6. Enable Diagnose mode, get the log of the camera, and share the log file.

How to Get the Log of Tapo Camera?

  @Dimak  Glad to know the problem was solved by changing to a 12V power cord when you use a power extension cable for the camera. 

Thanks for sharing solution here with community