If a wireless network is not visible, it must be added manually to the Xiaomi smartphone using the SSID (router access name) and, depending on the encryption or security, the appropriate password.

Android 10 (MIUI 12.0)
Step 1:  Open the  Settings
Step 2:  Tap on  Wi-Fi
Step 3:  Tap on  Add network
Step 4:  Enter the appropriate  data
Step 5:  Tap on  Save
  1. Open the Settings
  2. Tap on Wi-Fi
  3. Tap on Add network
  4. Enter the appropriate data
  5. Tap on Save

Xiaomi Instructions