Hi, I've asked a month ago the Xiaomi Global Service about this issue. Here is the answer:
"Hello, Greetings from Xiaomi Customer Support! This is Ida.
We at Xiaomi value your trust and we apologize for the inconvenience. Rest assured that we'll assist you on this. We would be grateful if you could share your country/region with us.
According to your description, I would like to request you to perform the following troubleshooting steps:
1. Check whether there is any special character in the Wi-Fi name, change the router's Wi-Fi name and password to English/number type, and then try to connect.
2. Please check whether the Wi-Fi password is correct. Select the Wi-Fi name, press "Right button" on the remote control, and then select "Ignore this network", and then re-enter the password.
3. Check whether the router turns on the DHCP function. If you turn off DHCP, the TV will not automatically get the IP address.
4. Check whether the router restricts more terminal access. If the router only allows whitelist devices to access Wi-Fi, add the projector's MAC address to the whitelist and try again.
5. Check whether the projector can connect to other Wi-Fi (such as mobile hotspot) : If it can, please restart or reset the router;
6. If it cannot be connected, please restore the projector to factory Settings and try to connect to Wi-Fi again.
We appreciate for your patience and understanding.
Hope the above information can help you. If you have any other questions, welcome to visit again. Always believe that something wonderful is about to happen!"
I think I've checked all of these before, but I'll do again,
beleiving that something wonderful is about to happen.....