Nighthawk router upgrade

I have had a Nighthawk R8000 router and two EX7000 AC1900 Netgear wi-fi extenders for almost 10 years with excellent functionality.
After an email from Netgear, to upgrade firmware in the Nighthawk router, it has died.
I decided to buy a new one, but need advice which model I should buy and if I should keep my wi-fi architecture and keep my EX7000 extenders.
I have 2floor house with a cellar and a big garden around the house. I need good wi-fi connections on all floors and outside in the garden.
My fiber internet connection and my Nighthawk router are placed in the cellar, with bad wi-fi environment for reaching outside the cellar. All the wi-fi antennas on the Nighthawk R8000 router did not work/reach outside the cellar. The EX7000 extenders are connected to the router with internet cables.
What new equipment should I buy?
I am very thankful to all advice I can get.