Xiaomi SmartMi Fan 2S problems - Wi-Fi MiHome app not connecting

My SmartMi Fan 2S arrived today, I’ve finished the initial device setup in Mi Home app. The process of pairing was slow, but in the end, it finished successfully.

And now 95% of the time I see the Fan as "Device Offline" in Mi Home dashboard. Sporadically, it becomes available for few seconds and I can even start firmware update, but the update process fails, it never ends successfully (now stuck at 15%).

It’s a chinese version of the device. I use the latest Mi Home Android app available in Google Play. I choose Chinese Mainland region.

I tried to connect the Fan to OpenHab. In Paper UI, I see how device status changes from OFFLINE to OFFLINE COMMUNICATION ERROR to ONLINE and then to OFFLINE - CONFIGURATION_ERROR. If I’m lucky, when it’s ONLINE I can toggle ON/OFF switch and it works (with a minute-long delay).

I’m unhappy with the purchase. I can’t use smart features. I can’t update the firmware.

How to fix the connection issue?

debug details:

hardwareVersion        esp32
mcuFirmware            0008
modelId                zhimi.fan.za4
vendor                 Xiaomi
wifiFirmware           v3.1.3-8-gce4d3fe10
Current firmware:      2.0.3

Phone: Google Pixel 2
Android 10
Mi Home app version 5.6.99 (the latest)
Router Huawei HG8245

What have I already tried?

• search for a solution on the Internet
• contact Xiaomi support
• disconnect the fan from a power outlet
• connect the fan to a power outlet
• bring the fan closer to the router
• remove the device from MiHome, reset WiFi settings, reconnect (Chinese Mainland region)
• remove the device from MiHome, reset WiFi settings, reconnect (Belarus region)
• clear Mi Home app cache
• Integrate the fan with OpenHab using the Xiaomi mi IO binding plugin (if I’m lucky, it responds to the ON / OFF command!)
• set DNS server to Chinese 114.114.114.114 (in router settings)

Screenshots: