Orbi RBR750 - No internet for Win 10 PCs on main WiFi network, but guest network is fine

Windows 10 PCs (one desktop, two laptops) can see and connect to main Orbi RBR750 WiFi network, but always get "connected, no internet" -- if I turn on Orbi guest WiFi network, they connect to that no problem (but then they're on the guest subnet and can't "see" the devices on my main subnet, such as my network printer--so this is not a complete solution). 

Other devices (including Android phones/tablets, game systems, Chromebooks, IoT devices) connect just fine.  Updated drivers for all computers' WiFi adapters, uninstalled/reinstalled the adapters, made various tweaks to Win 10 network settings per some threads online, but to no avail.  Those same PCs connect just fine to an older Orbi RBR50 with identical settings on the WiFi network.