How can two home networks interfere with one another?

2blue4u said:
*Cough*

Solution >



Switch off/disconnect all devices. Change the modem/router address. Pour glass of wine. Plug everything back in.
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Changing subnets isn't a fix. If the networks weren't physically connected in some way, then there's no problem using the same address range. The problem is that some device is forming a connection between the two networks. Every single house in my road with Virgin is using the same subnet for the networks, but they can't see each other. The same subnet is a red herring.
 
EightBitTony said:
Changing subnets isn't a fix. If the networks weren't physically connected in some way, then there's no problem using the same address range. The problem is that some device is forming a connection between the two networks. Every single house in my road with Virgin is using the same subnet for the networks, but they can't see each other. The same subnet is a red herring.
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Not physically connected, I hope. Unless the neighbour has strung over an ethernet cable :)

I agree there is an issue with a rogue device forming a connection. But unless it is found, which is proving to be a problem, then the subnet change will fix.
 
2blue4u said:
Not physically connected, I hope. Unless the neighbour has strung over an ethernet cable :)

I agree there is an issue with a rogue device forming a connection. But unless it is found, which is proving to be a problem, then the subnet change will fix.
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Not necessarily. The neighbours devices show up in Stewart's routers DHCP list which means that at least once the neighbours devices have been assigned an IP address from Stewart's router, if that is the case and the devices are getting an IP from Stewart's router then changing the IP will make no difference.

The fix is to find the link and sort that out. I'm still convinced that this is a power line device.
Stewart really needs to go around next door and have a look for himself.
 
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StewartR said:
They do have push buttons to set up pairing when first connected, and they do have passwords. When I set up the powerline adapters I used the push button to pair them. In theory that means they have set up a private network and my neighbours' powerline adapter should not be able to talk to them. In practice it seems that may not be the case. I will use the TP-Link utility to explicitly create a private network and see whether that makes a difference.
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If your neighbour has powerline adapters, and pressed his pair button at the same time, then they would have all paired together joining his wired network to yours. This may seem unlikely, but from what you've said this is not an ordinary problem. You also need to ensure that you enable encryption enabled on your powerline adapters. This will ensure that he can't join your network.

Looking at the big list of MAC addresses you posted, here is some more details on the "unknown" devices - the first 6 characters of each MAC is vendor dependent and indicates who manufactured the networking chips used in a piece of equipment.

c0-a0-bb D-Link
14-cc-20 TP-Link
28-c6-8e Netgear

00-40-9d Digiboard INC (these guys also make networking stuff: https://en.wikipedia.org/wiki/Digi_International)
00-23-76 Digiboard INC

00-1f-16 Wistron (these guys make tablets and notebooks for other companies - used to be part of Acer)
bc-30-7e Wistron

94-e9-6a Apple
0c-30-21 Apple

18-5e-0f Intel

68-94-23 Hon Hai / Foxconn (this company make consumer electronics for just about everyone - including Apple)

30-59-b7 Microsoft
7c-ed-8d Microsoft

00-13-a9 Sony

00-21-ed Telegesis (Home automation stuff)

f0-a2-25 Unknown (Private address range - no idea what this would be)

There's at least 3 different bits of networking kit there for definite (D-Link, TP-Link, Netgear), and the Digiboard devices could be network devices too.


Anyway, as others have said - I would definitely start by switching off your powerline adapters and see what happens.
 
One other thing you can try is to scan the wireless networks. I have a great app called NetSpot which has a free version. It is Windows and Mac compatible too: http://www.netspotapp.com
With this you can not only see the wireless networks that are available, but also which device(s). If there's a repeater, it will show up with the same SSID, but a different MAC address.

NetSpot will also show the frequencies in use, so you can try and avoid interference with neighbouring devices.
 
Turn off your routers wi-fi. Disconnect everything from the router bar one laptop/desktop, connected via Ethernet cable.

Can you still see the neighbours network? (You can use zenmap to scan a network from a PC.)

IF yes - then contact your ISP. I think this is VERY unlikely, but it's possible something is happening upstream of your routers. Your router should not pass traffic intended for your LAN (local network) over the WAN (internet) interface - which should not be the case. Your neighbours router would have to be doing the same thing and your ISP would have to have their network configured that packets are routed between your two networks. I know VM customers will find their WAN IP is subnetted with other people in the local geographic area - but on top of that something has to be very wrong in terms of configuration.
IF no - then your networks are somehow conjoined.

Turn off every other device - hard powered off if necessary.
Turn the Wi-Fi on, wait a while, and then scan.

Can you see the neighbours network?

IF yes: Change the Wi-Fi SSID / Key. Check that the router isn't configured with multiple SSIDs
IF no: Plug the powerline devices back in.

Can you see the neighbours network?

IF yes: Then your neighbour also has powerline adapters. Most powerline adapters are quite rudimentary and will behave in exactly the way you are experiencing here. You need to find a more sophisticated model of powerline adapter that will encrypt the traffic over the mains. Or better still, get some Cat 5E/6A installed.
IF no: Switch on other devices on your network, one at a time and re-scan the network. Allow a decent period of time to elapse between switching the device on and scanning.

If on activiating a device you see the network, you will find that device is bridging the two networks. Check it's wireless configuration carefully. Many devices run their own wireless hot spots, it's possible he has a device on his network that is joining to that hotspot giving that device a leg in both networks.


In order of probability, by my estimation:

1) Powerline adapters
2) Device inadvertently acting as a Wi-Fi bridge (lots of consumer level devices have terribly insecure default configurations)
3) Matching SSID/Wi-Fi keys (unlikely if you've changed the Wi-Fi key)
4) An upstream issue (EXTREMELY unlikely)


This is something that needs fixing properly and not bodging.
 
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Interesting one.

You wouldn't happen to have Windows Wifi credential sharing on for contacts would you? When close neighbours that could be the case.

Otherwise I would think its the home plugs or that other smarthome device that bridged the networks.
 
Had something similar with my fathers home network. On the odd occasion I looked, I noted strange devices pop up from time to time and put it down to the BT Home Hub. I understand that if you have Broadband through BT you are able to connect to other BT hotspots - and that includes sharing wifi through other peoples home routers. If next door has a similar provider and the device actively looks for a stronger wifi signal, it can connect kind of as a guest on your network. In theory it rebalances the data rate so that you don't loose the service you paid for.

My money is that is what happened here.
 
Tulipone said:
Had something similar with my fathers home network. On the odd occasion I looked, I noted strange devices pop up from time to time and put it down to the BT Home Hub. I understand that if you have Broadband through BT you are able to connect to other BT hotspots - and that includes sharing wifi through other peoples home routers. If next door has a similar provider and the device actively looks for a stronger wifi signal, it can connect kind of as a guest on your network. In theory it rebalances the data rate so that you don't loose the service you paid for.

My money is that is what happened here.
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These should never appear on the device list, even if the HH is set-up for this. They do not connect as a guest on your network.
 
Alastair said:
These should never appear on the device list, even if the HH is set-up for this. They do not connect as a guest on your network.
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I understand that they are not invited guests and that their devices should not show up. I think the other devices used to show up when next door kids turned up after school. If I remember correctly BT either updated the firmware of the Home hub or replaced it and believe it didn't occur again.
 
Tulipone said:
I understand that they are not invited guests and that their devices should not show up. I think the other devices used to show up when next door kids turned up after school. If I remember correctly BT either updated the firmware of the Home hub or replaced it and believe it didn't occur again.
Click to expand...

I "think" the BT wifi, broadcasts an additional network providing access to other BT users, it's possible neighbours could connect to the stronger signal if the network details were saved to the device. However they should never show on the host network, as I understand BT wifi is essentially a VPN, as an aside I suspect many/most people have this setup without any knowledge, as BT prevent it being turned off from the router only from the online account.

in this case it looked very likely that the devices were not connected by wifi, I think home plugs....
 
Tulipone said:
I understand that they are not invited guests and that their devices should not show up. I think the other devices used to show up when next door kids turned up after school. If I remember correctly BT either updated the firmware of the Home hub or replaced it and believe it didn't occur again.
Click to expand...

I "think" the BT wifi, broadcasts an additional network providing access to other BT users, it's possible neighbours could connect to the stronger signal if the network details were saved to the device. However they should never show on the host network, as I understand BT wifi is essentially a VPN, as an aside I suspect many/most people have this setup without any knowledge, as BT prevent it being turned off from the router only from the online account.

in this case it looked very likely that the devices were not connected by wifi, I think home plugs....
 
Tulipone said:
I understand that they are not invited guests and that their devices should not show up. I think the other devices used to show up when next door kids turned up after school. If I remember correctly BT either updated the firmware of the Home hub or replaced it and believe it didn't occur again.
Click to expand...

I "think" the BT wifi, broadcasts an additional network providing access to other BT users, it's possible neighbours could connect to the stronger signal if the network details were saved to the device. However they should never show on the host network, as I understand BT wifi is essentially a VPN, as an aside I suspect many/most people have this setup without any knowledge, as BT prevent it being turned off from the router only from the online account.

in this case it looked very likely that the devices were not connected by wifi, I think home plugs....
 
Tulipone said:
I understand that they are not invited guests and that their devices should not show up. I think the other devices used to show up when next door kids turned up after school. If I remember correctly BT either updated the firmware of the Home hub or replaced it and believe it didn't occur again.
Click to expand...

I "think" the BT wifi, broadcasts an additional network providing access to other BT users, it's possible neighbours could connect to the stronger signal if the network details were saved to the device. However they should never show on the host network, as I understand BT wifi is essentially a VPN, as an aside I suspect many/most people have this setup without any knowledge, as BT prevent it being turned off from the router only from the online account.

in this case it looked very likely that the devices were not connected by wifi, I think home plugs....
 
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