@Kevin_Z 

Hi Kevin,

Thank you very much for your reply!

Our network is at the moment completely connected using only UTP cables, except for the powerline modules, and the neighbours do not have our wifi login codes so they could not be connected via wifi.

I also called our internet provider, and they could confirm that there is no bridging between our houses in the glassfiber cables that connect our local networks to the internet.

Therefore, the only possible link between our networks could be the powerline network.

@Kevin_Z 

Allthough this seems to be a date post - I can confirm that I have experienced this issue as well. The Powerline adapter was connected to my Extreme Networks switch, and I can confirm that the MAC addresses that I recorded during this incident (I was able to get a DHCP lease from my neighbors DHCP server) linked to the ip addresses were all installed in the forward information base (CAM Table) of the switch on the port that was attached to the power-line adapter. 

I have my doubts about the integrity of the product, and will proceed with further investigating the reliability of the key exchange between products - as I have been capable to reproduce the issue 3 times, I have my doubts that the supposedly used AES native encryption as stated in your brochure has been implemented to satisfactory levels. 

It is a shame, as the product has shown to have some real potential for the hard to reach places in my home where cabling is difficult to install. Performance is also pretty ok.... but this security incident is an absolute no-go. 

TPLink staff, please stop pretending that this is a random event that happens to some only. Just have a look at the number of views of this post. Also a Google search would suffice too. You need to do something about that. 

Your suggested solution is this case is to setup a custom network name using PLC software. Although your PLC software has very limited features, this can be done. However, your instructions page says: "Now only the powerline devices using the same name can join this network". How do I make sure that my new powerline device use the new name?

On the other note, have you ever tried to find a pairing button on your powerline adapters? Not while they are on your desk, but while they are connected to the power socket located close to the ground behind the working desk that has 3 sides (common office configuration)? I bet not.

I also have TPLink ADSL network router and a range extender devices. Range extender is a joke in many aspects, wasted money. Very disapointed... 

@Joep01 

I have just noticed that my neighbor and I are suffering the same issue. It gets interesting though...

He has a pair of Netgear PowerLine adapters and I'm using TPLink PowerLine adapters. We're seeing each other devices on our respective networks as wired devices. On top of that we're able to control any device connected via wi-fi. 

Did you ever find a solution?

@ChrisHoppyBot 

Sadly, I have not been able to fix the problem. I have tried pairing the adapters again, and sometimes that worked for a while, but eventually, the networks always connected again. I also tried changing the internal keys, but could not find a way to do that with tp-link adapters (although I believe netgear adapters should be easy to change).

After a lot of trying to fix the problem, I just decided to circumvent the problem by buying a powerfull ubiquity router, which has great range and speed and has so far worked without problems.

The closest I ever came to a solution was placing some sort of denoiser / filter on the incoming power grid connection that would prevent any signals from outside the local electricity network from entering or vice versa, but it was quite vague what I would need exactly and I couldn't really find a place to buy such filters. At least not ones that could handle the current draw of an entire house and were also somewhat affordable.