Why my Xiaomi or Redmi can't send or receive anything?
This issue is caused by Xiaomi. You can try the follow the steps.
Find and open the Xiaomi Security Center --Click Data usage-- Click Restrict data usage-- Ensure all the "Ticks on mobile and WLAN" are checked.
Don't worry about why SHAREit need this permission. It is a wrong discription by Xiaomi mistake. Be as ease as SHAREit never use your moible data to transfer.