Hi, total newbie here. 

I have a Huawei 4G router. From this I run an ethernet cable to a TP-link AV600. Through the leccy, I have three TP-link extenders.

My house is very old and long, the thick walls cause huge signal drop off. The router in in the middle of the house

I was thinking about buying the Deco P9 (three Pack) bundle.

I would still have the 4G router connecting to the AV600, then placing the three P9's throughout out my long house.

My dining room, my office is at one end of the house, first P9 the living room and smart TV next, second P9.

My wife's studio would feed from the 4G router. And the third P9 would be placed near our bedroom at the far end of the house  

Any thoughts or suggestions would be appreciated.

Thanks and stay safe

Roy