@Federosario 

Hi, thank you very much for posting on TP-Link community.

1. Does the SSID configuration lost every time when you reboot the powerline extender? or just happens randomly?

2. Except for the SSID, will other configurations such as password etc. lose as well? which could confirm if it is reset to factory defaults completely.

3. Normally is your SSID on the powerline extender the same as that of your router or different?

4. For the OneMesh issue, please provide hardware and firmware version of both the router and the powerline extender, also share with us some screenshots to show the problem and error message etc..