Here's a tip for anyone with an AX6000 and devices with select Intel network adapters that won't connect without disabling ax on the router or disabling ac on the network adapter. Both of those fixes destroy WiFi speed and you also can't use smart connect when disabling ax. Instead go to the router system parameters and disable Short GI. As a side benefit enjoy a huge WiFi range boost. That worked for me and I hope it works for you.

I'm highly annoyed with this router as this was an issue to solve and also due to this router causing my WiFi printer to randomly stop working constantly.