trying to add third RBS850 satellite to RBR850 - will not sync

Thanks very much for your detailed reply.

I tried setting the laptop to 192.168.10.10 and the TFTP client to PUT to 192.168.10.250.  No luck.

I tried various settings, such as "Private Network" or "Public Network".  I tried setting the laptop to 192.168.10.10 and 192.168.1.10.  Neither seemed to work.

When using TFTP to update firmware on switches, I'm used to the laptop acting as a TFTP server and the switch makes the initial TFTP request.  The firmware file is placed in the TFTP root and is the only file there.  So, it seems unusual to me that the laptop needs to be a TFTP client and it needs to "PUT" the firmware to the Orbi.

I never got TFTP to work.

It took me a LOT of searching to find out how to do a "factory reset".  It looks like you push the reset button for 15 seconds until the LED turns yellow and blinks.  You have to wait until it blinks.

Other people talk about 30/30/30 but never explain what that means.

Sometimes a simple push/release of the reset button causes the LED to go yellow and then back to green.

I just wish that Netgear would publish simple instructions for how to do a reset and if there are multiple kinds of resets, how to do each one.

Here's what FINALLY worked for me:

1.  hold reset button for more than 15 seconds and wait for the yellow LED to blink

2.  set the laptop with the static IP 192.168.1.10 / 24 (255.255.255.0), gateway 192.168.1.1, DNS anything (I chose 192.168.1.1)

3.  bring up Edge browser and go to the URL http://192.168.1.250

     It looks like the web page will only come up after a long (15 sec) factory reset

4.  log into the Satellite's web page with admin and password (yes, the password is password!)

5.  go to update firmware and select the firmware file.  wait for the update to finish and the Satellite to reboot.

6.  go to the Orbi admin GUI, "Basic", "Add Orbi Satellite" and go through the steps

7.  in the Orbi admin GUI, "Advanced", "Administration", "Attached Devices", the new satellite now appears in the list!!!!!

     but, it says "Out of sync"

8.  Press the "Sync" button on the back of the new Orbi satellite

9.  FINAL SUCCESS, it is synced and working

Maybe these steps will help others with similar problems.  Thanks again for your help.