Hello I was hoping to solve some problems I'm having with my home and office wifi. Some background: I recently bought 2 iMacs and a mac mini for my office which is part of my home. We are still in the process of retiring our PC's as they are running software that we need to work. The mac mini is being used as a server (I'm not running any server software however) and will have all of our office files as well as an external drive for all of our family's photos, videos, movies and music. The two iMacs are running Lion and the mac mini is running Mountain Lion (10.8.2). Now for the issue. I also have an apartment attached to my house that I rent to students at the local university. I provide them with wifi. I have a 5th generation Airport Extreme. I could not use the guest networking option for them because that network cannot be extended and they do not get signal for it. So, I set up two parallel networks. One with my new Airport Extreme for my home and office and another for the students using my old Airport extreme. The two Airports connect to the same ADSL router. Two different wifi networks, two different passwords. So why do I see their computers on my iMacs? The whole purpose of all of this was to isolate them from us. I'm assuming because they share the router they can see anything on the either network. Are there any solutions to this or is the only option a second phone line and router?