What happened when 4g became 2g?

The reasons why mobile phones suddenly changed from 4G to 2G: 1. Network congestion. When the number of users in the network exceeds the carrying capacity of the network, it will cause network congestion; 2. Signal coverage problem, the signal coverage of the 4G network is relatively Narrow, especially in remote areas or cities with dense high-rise buildings, 4G signals may not cover every corner; 3. Equipment failure. Failure of the mobile phone or the device itself may also cause 4G to become 2G; 4. Operator strategy Adjustment: In order to reduce network costs or adjust resource allocation, operators intentionally downgrade some areas from 4G to 2G.