@Rondh If you change the wireless password of your X60, you'll have to change that password on every devices so it could reconnect.

@kingboa Try setting your FritzBox 7590 AX 5GHz radio on a wireless channel 36 and test if the TL-WR902AC will see its SSID.

@Brianzs Check this post regarding your issue.

@Horsepower I would suggest to search for this particulat issue or post a new thread in the Deco support forum section and if it's been resolved, just buy a Deco unit.

@NGSC Once you've added A8 as a satellite device you'd lose its management interface access - that's by design. It should be managed trough the Onemesh device list menu of the GX90.

@Horsepower Access point mode , WAN port is the short answer (details - Case 1), but why don't you buy an additional Deco unit to extend your network keeping the mesh in your premises. AX3000 won't...