Recomended Settins on my AX8 RAX80 for best stability with my Extenders

I just upgraded my Nighthawk R800P router with an AX8 RAX80.

I've got a large home and extend teh wifi to parts of my property.  I had the EX6400 upstairs and the EX8000 in a corner room of the house to extend a single WIFI SSID around the home.

I though the AX8 would provide greater stability but it's been a little flaky.

I've tried disabling bells and whistles on the RAX80, but the internet still seems to be a bit more intermitten than I would have hoped. 

Prio to the upgrade the R8000P would have to be power-cycled when internet dropped around the house or for specific devices.

Do you have any recommended settings to make everything a bit more stable for all devices?