Taking a look in the system log, I found many errors related to DHCP such as DHCP server stopped, DHCP detection failed. Obviously, I think the DHCP is faulty.

@PleaseHelpMe I am using RE200. To be honest, as it is such a pain having the same symptom. What I found when connected to XXX_EXT, the DHCP assigns the default gateway as 192.168.1.254 which is the...