My brother is my neighbor and we are saving some money sharing internet, but I don't want to share anything else, just internet.

What I did is to pass a cable through the wall that connects his router —that has access to internet— to my router. I created my own wifi name and password.

Today my brother-in-law has been listening to online radios and I had the notification in my android phone telling me that someone was casting in a wireless sound system.

I checked my router entering its IP in the explorer url box and saw that someone "unknown" was connected to my network.

I would like anything connected to my wifi to stay in a different network, being not able to see what my brother is doing (and vice-versa)

How should I start?

  • I'm voting to close this as off topic for iot. This is really a consumer grade networking question and would probably be right for superuser.com
    – hardillb
    Commented Jun 26, 2019 at 21:28
  • It is, although there is a lot of overlap between the understanding of network topology needed to understand this problem and that needed to successfully implement and deploy IOT devices.
    – cmm
    Commented Jun 26, 2019 at 21:38
  • Yeah, sorry, but @hardillb is right; this isn't actually the best stack for this question. Glad you got an answer anyhow. I've closed it now so that future users don't think that this is the best place to ask similar questions.
    – anonymous2
    Commented Jun 27, 2019 at 2:13

1 Answer 1


One way to get some isolation between your wired networks is for each of you to have your own dedicated router. The WAN port of each of your routers is wired to a LAN port of the ISP's router.

To the ISP router, there are only two clients, Router You and Router Brother. Each of the You and Brother routers are configured as normal for a router. They have their DHCP servers enables. They perform DNS caching. They have their WiFi on with your choice of SSIDs and credentials, different for each of you. When a request from your side is made, it is NAT'ed out of your router and into the common ISP router. There, it is NAT'ed again and presented to the wild Internet. Same for your brother.

There is no internetworking between you and your brother. You share an ISP connection.

Although anything is probably hackable, short of exploiting a bug in the router, neither of you can probe the other's network.

  • Nice! Thank you. Looks pausible, I just need to buy another second hand Vodafone router. We both have already a Sercomm Vox 2.5. However, I had to deactivate DHCP in my router for it to work with my brother's. I don't know why. Could I, then, turn it on once we share a common ISP?
    – riqui
    Commented Jun 26, 2019 at 22:04
  • 1
    You will have the routers in a Y. Wan ports on the individual routers connected to Lan ports on the central router. Wan on the central connected to the ISP. Dhcp on on all routers.
    – cmm
    Commented Jun 26, 2019 at 22:45
  • What I finally did is to connect one router's WAN to other router's LAN, which is connected to internet. Each of the routers creates its own local network and they only share internet. I think it works as I pretended, and I only needed 2 routers. Thank you.
    – riqui
    Commented Dec 14, 2020 at 10:19
  • 1
    If the topology is router2 wan -> router 1 lan, router 1 wan -> internet port, then all clients of router 2 can access all clients of router 2m. You have made router 1's network inaccessible to router 2's network, but not the reverse. If this is your purpose, you are correct that you need only 2 routers.
    – cmm
    Commented Dec 14, 2020 at 11:25
  • Thank you. What does exactly mean that router 2 is accesible by router 1? Router 1 is my brother's and I know he is not going to try to access router 2, but I am curious. As far as they don't share a network it is valid for me.
    – riqui
    Commented Dec 15, 2020 at 12:41

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