Can't connect some devices to wi-fi network after installing Orbi router and two satellites.

JM,

A few quick things you can check, if you haven't done so already:

• What cable modem do you have?  When I had similar problems last year, our cable internet provider's tech support team was helpful in conducting some tests that pointed to a failing cable modem.
• What was your previous router?  If you still have it you can plug it in, compare the settings on the old router to the settings on the orbi router, and see what is different. One of the default settings may be causing a problem.
• You mentioned falling back to your old extenders, but didn't mention the old router -- on the outside chance you are using a cable modem/router combo from your cable company, you may have inadvertently set up a second WiFi network (one for old router, one for new).   You'll probably need to turn WiFi off on the old cable modem/ router.  
• When our ISP rolled out IPv6 support last year, many of us with a specific router had lots of problems that required settings changes and a firmware update from the router provider.   You could check the IPv6 settings on the new router.  My Orbi came with IPv6 disabled by default, which means it is supporting IPv4 connections only  (a subject of debate on these forums).  In case yours has IPv6 enabled, you may want to try disabling it and see if that changes anything.

Good luck!  I am very pleased with the one satellite Orbi I set up last week.  It is performing very well for us. 

js