I tried to add to the previous thread on adding an Apple Airport Express to an Orbi network, but couldn't figure out how - so here I am with a new "conversation".
In any case, I just wanted to add - I moved to Orbi gear, and sold my Airport Extremes. However I still have 4 Airport Express's and wanted to connect them. Everyone says put them in Client mode, but no one tells you how - except for a short blip from Apple - but that's using the base router. Or a new AX I guess (which don't exist btw). In any case, mine weren't showing up on the AirPort Utility (well, one was, but no idea why that one was different?). In any case, with no Airport Extreme and nothing in the AirPort Utility - how do you set the AX's to Client Mode?
Ultimately I found that by doing a Reset, they now show up in the Utility. From there, you can Edit their configuration and "Add to Existing Network" (under More Options). Then wait for them to reset/rebuild and they'll show up and you can plug speakers in. Haven't tried a printer (which Apple says will also work.)
The key is the reset. To reset the AX - there's a small, recessed, reset button right above the stereo jack port. You push and hold that while plugging in the power. Hold it until the yellow light on the front starts flashing (about 5 seconds). That means it's resetting. Within a couple of minutes after getting a steady yellow light, it should show up in the AirPort Utility. Then go from there.
Good luck and hope this helps someone - I searched quite a bit before I found everything I needed.
I don't know if this will help. I have an Airport Extreme that I setup on my Orbi network. When I setup the wireless, I used the "Create a Wireless Network" option and setup all of the SSID, password, Wireless security, etc the same as on the Orbi. My devices roam just fine including Wifi Calling on my iphones between the Airport and the Orbi.
