Orbi 750 Tri-band mesh wi-fi 6 system - Set-up advice & Connection issue

I will try that.  I'll need to look up how to set it in modem only, but can't get to it right now. I'm assuming I can find that info on this site somewhere.  Other problem is that now, besides the tv & Echo, my printer won't connect via wi-fi.  Should I do an initial set-up rather than what I did (add device)? I'm thinking that may be part of the issue, but don't want to power down my husband's businesss side since they run off of my network.  Unfortunately, we're all a little technologically challenged - them more than me.

The router unit is not plugged into the system right now, just the additional satellites.  They're all showing as connected, but aren't showing up as a connection point.

thanks for your response - I really appreciate it.

Hi again, 

The biggest issue is not the the separate router.  I really don't need to add that to my configuration if it's not going to improve anything or make any difference.  

My big problem is that devices that were previously connected are no longer connecting.  It started with my iMac, but was resolved by changing channels & LAN setting, per support person.  My LG is also not connecting, but support couldn't help there. Not real sure if settings need to be changed there & what they should be.

I'm also unable to make a connection to my printer (Canon) & my Amazon Echo. All devices recognize the Orbi, but can no longer connect. I've rebooted everything, reset the Orbi, done the updates, but still nothing. I have not done a reinstall as yet, but I need to, can you let me know if there's a particular step I need to do? Unplug satellites, delete app or where to find best guide? 

I did add 2 more satellites, but problems existed before that & that didn't seem to negatively affect the system. My app shows everything online/working. My iPhones, iPad, EV all have Wi-Fi, so I'm getting a signal from Spectrum. I'm just dumbfounded as to why all these other devices stopped at about the same time.

Any suggestions would be greatly appreciated. I'm not real fluent in tech speak, but can follow along if I know where to go.