Orbi loosing Internet Connection

I have had my Orbi RBK50 for a week or so.  It is set in AP mode with my Comcast modem/router as my primary router.  I am very frustrated that the Orbi keeps losing internet connectivity, sometimes once a day, sometimes 10 times a day, requiring a reboot.  When it works it works GREAT, but I can't really stand the fact that it is constantly going down.  Meanwhile, the WiFi from my Comcast modem router never goes down.  I want the throughput and the range of the Orbi, but it is totally unreliable.  The firmware is the latest version (2. something).  I see from the community message boards that this is a regular problem with a lot of folks, with no resolution.  Right now I want my old Airport Extreme routers back (I used two--one to establish the network and the other to extend the network).  The problem with the Airport WiFi was that the speed at the end of the WiFi network was terrible, whereas when it is working the Orbi blazes.  Having said that the Orbi is totally unrelable.  Right now I have most of my WiFi devices hooked into the Comcast WiFi because I can't count on the Orbi to work.  Any help would be greatly appreciated.