The client cannot obtain the IP address after the network extension function is started.
Cause one: There is no reachable route between the virtual gateway and the DHCP server.
Cause two: The DHCP server is not assigned with an IP address.
Cause three: The virtual IP address (for network extension) assigned on the DHCP server or from the address pool conflicts with other IP addresses on the device, which results in the assignment failure.
Cause four: The DHCP client service in the OS of the user PC is disabled.
Cause five: No IP address in the address pool can be assigned.
Cause one, cause two, and cause four may occur only when the DHCP server is adopted to assign the virtual IP address for network extension