Thanks!!!! I compared mine and yours LOGs. There is a difference in the order in which system components are loaded, but I don’t think it is important. I also have PPPOE, and you have DYNDNS. I will...

@maciejp Yes, I tried it. Hardreset, new SSID, two devices ... Could you post the router log immediately after it reboots and connects wireless clients? Remove MAC addresses as I did.

@maciejp Have you changed the number of wireless clients? Maybe it's some kind of client that affects the router?

@maciejp Have you changed the SSID, or left it the same? I think it's not about the language. I have a few more ideas for experiments, I'll check it later. I think it's a matter of what and in what...

@maciejp I did a lot of experiments with factory reset. The result is negative .... Language does not matter...

No, it doesn't work. Anyway, after reboot, there is no connection ...