Did you buy a new one or they sent you a new one? I put in Contact with them and they ask me for my AAWireless-****** device number. Lets see what they say. I Will put here as soon as they answer me.
Edit:. They answer me: "This is unfortunately a phone side issue which we cannot help with. You can try different Wi-Fi channels using the companion app.". I tried several channels and nothing... So It is Xiaomi problem. Hope the fix It soon.