@Kevin_Z there is the problem that in latest firmware is not possible select choice WPA-PSK with AES encryption. Available is only with TKIP

After downgrade firmware and some tests it seems the problem was with Encryption TKIP . When I'm use AES only it is working without problem to now.

@Kevin_Z I'm sorry but the issue happen again now. My current settings are: Have you any solution of this problem?

Last night I changed the mode to the 802.11 b/g/n mixed and now I'm waiting what will happen. On 2.4Ghz network are IoT devices - about 20 . On 5Ghz are mobile devices and laptops.

I have the AX 73 router in AP mode, the OFDMA and TWT are off but the problem is still happend. On 2.4Ghz wifi are disconnected all devices, SSID is still visible and the 5Ghz wifi is work normally....