RBS50 always offine

Thanks for the info.  Again, we assume that the Orbi is connected directly to the Arris and that the switches are connected to the Orbi (or satellite) not to the Arris and not between the Arris and Orbi.  I have no experience with smartphone apps and Orbi.  I always use the web interface from a web browser on my PC (although others use laptops, Mac's or tablets).  And, I prefer to use a PC connected with Ethernet cable directly to a port on the Orbi.

I guess we sort of neglected to ask "are things connected to the satellite and working?"  Are you concerned because the Orbi app says the satellite is not connected and not because "devices aren't working"?  My first step would be to connect a web browser to the router and check the Attached Devices page to see if it matches the Orbi app.