@chaakoob I believe that's normal. AX90 supports these wireless standards: A tri-band RE like RE815XE supports: So, even you buy a tri-band RE it won't extend the second 5Ghz band of AX90:

@Raunak_Extender If after reset the RE is not responsive it could probably went faulty. Best contact your local tech support for further assistance.

@Big_Daddio "It looks like you aren't connected to your TP-Link network." This message usually comes up when you're not connected directly to the router wireless radio. You mentioned that you have...

@Krunopin It's about your local management password that can be changed here: If you don't remember this password the only way to resolve this is to reset the RE to its factory defaults and...

@Rudi-F Archer AX73 supports 802.11ax on its 2.4GHz band: If a wireless client that doesn't support that standard has issues connecting to the router you can set 2.4GHz mode like so:

@xyloPL This router model is provided by ISPs and in general they should provide any new FW releases to its customers.