The present disclosure discloses a method and network device for maintaining captive portal user authentication. Specifically, the disclosed system determines an association status between a client and an access point in a wireless network, as well as whether to remove an entry corresponding to the client from a network layer (L3) cache based on the association status. If it is determined that the entry is to be removed, the disclosed system removes the entry corresponding to the client from the network layer (L3) cache. Note that, the association status can be determined based on one or more of an indication by a station management process at the network device, and a detection of radio link activities.