Yesterday I installed FW (3.0.0.4.388_33144) on my AX4200, so far, I haven't encountered any problems, all devices are connected, at least 14 Wifi devices, iPhones, Android phones, printer, IoT devices, 7 devices via cable, all doing their job flawlessly for 24 hours now. Of course, I read the comments and prepared myself for the worst, but no problem, I restarted the router a few minutes after the update and it has been doing its job ever since.