Répéteur WIFI EX6470

Hello, i 've got a trouble installing mesh network. My wifi router is connected to my box, ethernet mode, and i need to extend my network to be connected in all my house. I have added a first extender AC1900 NigtHawk EX6470, which i configured as an extender with same network names (for 2,4 and 5g) as my router. I want to install a second NightHawk EX6470, which is normally Mesh compatible but no way to extend network from the first extender, only from the router. I would like to know if this model is really a mesh extender? Thank's to the community to give me answers if you know. Installation of this second extender has been done succesfully, but i don't find a parameter which indicates me "MESH"