I'm developing an app/server. The server is running locally on my laptop. At home I look at network utility (Im on OS X) which gives my laptop's local ip address. On my phone I tell the app to connect to that ip for testing. This works fine. Usually addresses are or something like this.

But today Im in a (big) public library, with lots of people using the free Wi-Fi. The above process to connect doesn't work; My computer's local ip looks more complicated ( Is there a way to connect the devices?

  • That "local IP" is actually a WAN IP; did you mean ""? – tyteen4a03 Jan 27 '17 at 16:11
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    Because the library isn't assigning a public ip address to your laptop. You won't be able to connect to your laptop from you phone while your at the library. – Ramhound Jan 27 '17 at 16:11
  • @tyteen4a03 yes I wanted to obfuscate it... not very smart from me :) – Thomas Jan 27 '17 at 16:55
  • @Thomas LAN IPs (,, are IPs used in private networks; those are assigned at will by the router of your network and doesn't mean anything outside the network. – tyteen4a03 Jan 27 '17 at 17:08

It's most likely because AP Isolation is on; this prevents clients connected to the same wireless network from communicating to each other as a security measure. This is usually turned on in public networks so hackers can't just go around the network scanning for vulnerabilities in other people's devices.

I would suggest setting up your own Wi-Fi hotspot instead of relying on the public Wi-Fi network if you want devices to be able to talk to each other over LAN.

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