Why does my wifi extender show as having two ip addresses.

Hello
I have a nest doorbell which connects via my wifi extender. The wifi extender has a static IP address set. The nest doorbell also has its IP address reserved on the routers DHCP table.
When I view the devices my Nest doorbell shows as an IP Camera (that I can understand) but with the IP address of the wifi extender and shows +2.  The second IP is that of the Nest doorbell reserved.
Further down the table, my wifi extender (TP-Link WA854RE) shows as a WiFi Extender but has no IP displayed and in notifications, shows a warning of "Some device is not able to get in network".
Tagged:

Answers

  • BK303
    BK303 Member Posts: 23
    10 Comments Name Dropper 5 Likes First Anniversary
    ✭✭
    edited December 17, 2020 #2
    It sounds like the WiFi extender you are using is setup for  a non-transparent Bridging mode,  which causes the MAC address of the Nest Doorbell  WiFi client device to be lost and replaced with the MAC address of the WiFi extender for packets sent back to your main WiFi station.  In this mode, the WiFi extender learns the IP addresses of the Clients and forwards the traffic appropriately that comes back with it's own MAC but has one of its clients IP addresses.   In this situation, Fing or Fingbox scan would see all the devices associated (wiFi connected) to the WiFi extender as having the same MAC address.  Unfortunately, Fing app then is fooled into thinking there is just one single physical device with the "+2" indicating that device has more than one IP address associated.   If the wifi extender is still showing up separately in the device list, Fing app may be thinking that was an older device with same MAC address, or perhaps the WiFi extender device has a second MAC address that is used for its own management interface when a wired connection is made or if no clients are currently associated to the the extender (?).  I can see how that behavior might confuse the Fing app.   I don't know if Fing app has any ability to separate multiple devices behind an Ethernet bridge sharing a single MAC address.  In theory, it could separate them based on IP address instead of MAC. 

    In any case, the best way to avoid this behavior of multiple devices with single MAC would be either use "WDS" mode for the extender (both your main WiFi and the extender need to support this) or run an Ethernet wire from your home router to your extender and use the WiFi extender in a standalone WiFi "Access Point" mode (not WiFi + NAT router, nor WiFi + bridge).  

    References to learn more:
    https://en.wikipedia.org/wiki/Bridging_(networking)
    https://www.excentis.com/blog/operation-wi-fi-bridges
  • BK303
    BK303 Member Posts: 23
    10 Comments Name Dropper 5 Likes First Anniversary
    ✭✭
    edited December 17, 2020 #3
    Just thought of another issue.  For the DCHP reserved IP for the Nest Doorbell, is the IP reserved using the MAC address of the Doorbell or the Wifi Extender?   Honestly, I'm not sure how multiple devices behind a non-transparent Bridge use DHCP to get unique MAC addresses.  Normally the DHCP server assigns one IP address to one MAC address.  I'm sure there is a mechanism that I'm not familiar with, and perhaps that mix of DHCP behavior for the reserved IP address is what is further fooling the Fing App to report that "Some device is not able to get in network" as it may think there is IP address collision between the Wifi Extenders MAC and the Doorbell's MAC. 
  • Netreg
    Netreg Member Posts: 3
    Photogenic First Comment
    Thank you for taking time to answer. 
    I have set a static IP on the extender for the extender.  The doorbell IP address is reserved via my router in the DNS table. I don't generally differentiate using mac addresses. My doorbell shows in my list of devices but has no IP address listed.  But your explanation helps