Google Fiber + Orbi X4200 RBR750 in the NC Triangle Area

Update - Just for good measure I wanted to eliminate Google Fiber as a possible culprit. As explained below, Google Fiber is not the problem. They've been great and very reliable. I'd still recommend them highly. 

So a Google tech came out very recently and verified the set up. No errors, everything was hooked up correctly, the backend people got all the proper responses. So I want to exonerate Google Fiber and say their service still is overall excellent, reliable, and quick. 

I asked the Google Fiber tech to let me borrow the complimentary Google Wifi Mesh points that come with a Fiber install so I can verify that's it's my Orbi router. He gave me the standard 2-pack of them, one to be used as a router and one as a satellite. It's not as fast or fancy as an Orbi RBR75X AX4200 but you know what - these cheap Google Wifi mesh spots have been working flawlessly. The internet connection hasn't dropped once and if I'm honest, the connection isn't that much noticeably slower that my Orbi setup. I'll gladly trade 50-100Mbps of wifi data speed advantage the Orbi offered for what is already a 100% reliable connection using these Google Wifi mesh spots. That is, 350 Mbps of extremely reliable internet access, being up 100% so far >>>>> 450 Mbps that's randomly cutting out during meetings and gaming sessions and messing up my IoTs. 

So I'm now in high 90s in confidence that my internet troubles of original post were caused by my Orbi and Orbi alone. And that is incredibly upsetting, given the money I/we spent for it. I confirmed the settings from Orbi are virtually identical to the Google Wifi Mesh, so this really, really seems like an Orbi firmware issue or similar.