@Nunopereiraa Tap on the smart plug, then go to "Device Settings" icon on the top right. Look at the signal strength. For a reliable connection it should be -70 dBm or lower. If the number is higher, then the area you have the plug in is not ideal as it is not getting a reliable signal and needs to be relocated.

If the signal strength is good, do a completel factory default by holding the small button on top for 15 seconds, and install the plug again.

My sinal strength is -61dBm . I already reset and reinstall and i have the same problem. 

@Nunopereiraa Might be best to get in touch with our support team to see what other solutions can be offered: https://www.tp-link.com/us/support/contact-technical-support/#LiveChat-Support