Devices and router's MAC and IP address/connections query

Hi all Firstly my setup... it is a Sky router connected to the phone line for fibre broadband. I then have a repeater set up as a client which is connected to the Sky router's 5G wifi, which in turn is connected to a old obsolete ISPs router by ethernet cable. From the second older router (the one not attached to the phone line) is a Netgear Extender which is connected over a distance of approximately 50 metres this time by 2.4G wifi.
From looking at the attached devices on each router, I have noticed that any computer connected directly to the Sky router's 2.4 or 5g wifi (I don't have any wired ethernet connections coming from the Sky router) also shows up as a connected device on the other router, but only sometimes does the Sky router show up as a connected device on the second router and all other devices directly connected to the Sky router don't show up at all on the second router?
Also, I am always able to connect and log into the Extender's admin page when there is a device connected to the extender's wifi, but not always at other times when there isn't? The device that is connected to the extender's wifi is given a virtual MAC by the extender (its actual MAC is also displayed), but that device is never shown as a connection to the older non-Sky router, even though it is connected to the extender which in turn is connected to the said second router's wifi? When I check the connected devices on the Sky router, the device which is connected to the extender, has the same MAC address as the second router (but not the virtual or real MAC listed on the extenders connected devices screen, but does have the same IP as listed on the extender's connected devices screen. Having said that though sometimes the device connected to the extender is showing up as the IP and MAC address of the second router (it fluctuates between the IP showing on the extender's connected devices screen and that of the second router).
I find this very puzzling, does anyone have any ideas? Is it something I should be concerned about? TIA

Edited by deleted (Thu 06-Sep-18 00:47:46)

Just to add, when I am able to connect and log into the extender's admin page (always connected through the Sky router as I don't want to connect to the other router's wifi which is on a separate SSID and password) I find that the second router shows as a connected device on the Sky router, (but never the extender). When I am not able to connect and log into the extender's admin page, the second router doesn't show up as a connected device on the Sky router. Hope this makes sense...

After a bit of research I think I have solved some of the above. From my understanding when a router forwards a packet it changes the MAC address of the routed packet to its own MAC address. From my understanding the Extender is a proxy connection, which is why it's not listed as a connected device on the second router's connected devices list and why its IP address fluctuates as packets are routed between the second router and the proxy extender connection/end device, while the packets always carry the second router's MAC address. What I don't understand is why computers connected to the Sky router always get listed in the second router's connected devices list, but not other devices. Are there any experts out there please able to help. TIA

Hi all. For anyone showing an interest in this thread, I think I now know the answer to the not all devices showing as connected on the second router. I believe the answer is IPv6. Not all my devices have a IPv6 connection, those that do show up as connected on the second router. I think it might have something to do with IPv6s NDP, but that is purely speculation on my part. All opinions welcome

I think my original thoughts could be wrong on this. I have just looked at the attached devices on my Sky router and there was a device listed there with a IP of 192.168.0.207, This device wasn't showing as connected to either the second router or the extender. I pulled the power on the client repeater, leaving only access via the Sky router, and predictably this device is no longer showing as connected! The extender is sitting in a neighbours house which I don't have access to. Are there any experts out there who could shed some light on this please...

Have tried to get my head around it, but suspect without being on site to see the physical and map out all the IP ranges and IP in use everywhere it may remain a mystery.

Thank you for your reply The second router and extender are on the same network segment as the Sky router. One of my neighbour's devices shows up as a connection on the extender's web interface witb a IP of 192.168.0.200. My concern is the ones that don't. Do you know by any chance if a randomised MAC address could cause this?

Edited by deleted (Mon 17-Sep-18 22:36:07)

Hi,

A randomized MAC address could cause this but it's HIGHLY unlikely IMHO. It sounds like you could do with tightening your security on your routers. Do you use a strong password with special characters (e.g. £$!/ etc)? I have set all my routers not to broadcast their SSID and I use MAC address filtering to try and make sure that only authorised devices can access my network.

HTH,

Thank you for your reply, time and input One of my concerns I guess is someone changing their MAC address to that of my second router/extender. Do you think this could produce the symptoms I have described? I'm on holiday at the moment and as a precaution I have pulled the power on the second router. Like you mentioned it's probably time to review the equipment in use... Any recommendations? :

Well I have configured the extender with a different passkey and disabled DHCP on the Sky router and changed its IP range. I have just checked my Sky router's interface and the extender is listed on it as a attached device with a MAC address of 80:3f:5d:fb:96:13. When I researched this MAC address it appears to belong to Winstars Technology Ltd. who make access points amongst other things!? This MAC address is unknown to me and doesn't match my neighbour's extender or his laptop, or any other equipment that I am aware of? I have disabled the PIN on the extender, but maybe WPS still works despite that? Plus there is a ethernet port on it! I also configured the extender's access control list to only allow the neighbour's laptop. As per normal though when I look for attached devices on the extender's user interface, there is nothing listed there and this MAC address lost connection to the Sky router once I broke the wifi link to the extender. Please help...