Someone else on my network

[#1]

Hello,

    I recently came across some devices I didn't recognise on my network. On further investigation I found another router at address 192.168.1.254 (mine is at 192.168.1.1). I can view the summary page in a browser and it's a BT Home Hub (mine is a TP-Link). That router is assigning an IP to devices and my router assigning to my devices but somehow our network is 'bridged' and we can see each others. 

Has anyone experienced this or know how to sort it? I've tried setting my router to 192.168.1.254 to no avail, rebooting the router, turning off wi-fi (just in case).

I have called up support who have assured me that no one else can share my static IP and they must be physically connected to my router which they are most definitely not.

In the first image - my router shows some wired clients when I have only wireless currently attached. When looking at the second image, you can see 'Bryans-MBP-2' showing as a wireless device on the foreign router when it is a wired on mine. One of my wireless devices 'Win-Laptop' shows as a wired client on the foreign router!

Can someone please help. I've had to lock all my open network folders down currently. I don't like the idea of a third party being on the same network as me.

[#2]

Are you using any homeplugs?

If so you are probably picking up a neighbours network.

[#3]

I am. I will investigate that. Thanks for the suggestion. Should have posted here first rather than spend an hour on the phone!

[#4 · Accepted solution]

Before I read Browni's post I had exactly the same thought - and that is very simple to test - just unplug it from the router and see if the other router disappears.

If it is the case it means both you and the other person are using homeplugs without setting up the security. Just you setting security should fix it.

[#5]

Thanks guys. Seems the neigbour has a couple of tp-link plugs as well. Removed them from the network and added security and all sorted.

Thanks again!