ok after some more checking this is what's going on, devices with wifi 6 can connect to this router ok, but devices with wifi 5 cannot. Is this router not backward compatible to wifi 5?

  @namsilat 

Hi,

The ultimate test would be to go to the menu "Advanced" > "System" > "Backup & Restore" and perform a full "FACTORY RESTORE".

After the router has restarted itself try to connect your wireless devices to the default Wi-Fi networks "TP-Link_xxxx" or "TP-Link_xxxx_5G" using the default password printed on the label that is stuck to the underside of the Archer AX1500.

Should this not work as well, then there might be indeed something wrong with your particular AX1500 device.

namsilat wrote

ok after some more checking this is what's going on, devices with wifi 6 can connect to this router ok, but devices with wifi 5 cannot. Is this router not backward compatible to wifi 5?

  @namsilat 

Make sure that "Mode" in the menu "Advanced" > "Wireless" > "Wireless Settings" is not set to "802.11ax only".

Apart from that, yes, there have been occasional reports of some older wireless devices not being able to connect to Wi-Fi 6 (AX) routers, but it would be quite a coincidence if you happened to own a whole bunch of non-Wi-Fi 6 wireless devices of which every single one is experiencing this issue.