@Rafa_F_R_40 

Hi, welcome to the community.

May I know how long you have had the Deco P9?

Here are some suggestions for your reference:

• More Deco away from high-power home appliances.
• Plug it directly into the wall power socket, instead of using an extension panel.
• Hold the reset pinhole for 1s to run a factory reset and set it up again.

If the noise continues, it is suggested to contact the local support to see whether the device is still under warranty:

https://www.tp-link.com/es/support/replacement-warranty/

Thank you very much.

Best regards.