Why is it important to avoid a situation where the SSID remains the same and the upper vlan changes in wireless network planning

Why is it important to avoid a situation where the SSID remains the same and the upper vlan changes in wireless network planning

For the terminal, it does not sense the vlan, for which only the SSID dimension to determine whether the network changes; when the SSID remains unchanged, the background equipment forcibly changes the terminal vlan, the terminal will still use the old vlan address segment for external communication if it does not take the initiative to update the address, resulting in service interruption, only after the terminal has sensed, the terminal then change the address, the service can be restored. So the wireless network planning try to open three layers of roaming (V7 default open), while the upper layer devices will be put through the corresponding vlan. Or use vlan pool technology.