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View Full Version : All devices switch to another network's router but remain on my SSID




pullman
Dec 27, 2012, 10:42 AM
This began today and it is driving me nuts.

I have several devices connected to my wifi - two iphones, an Air, a Mac Pro and an Apple TV. Today they developed connection problems.

Looking into their settings I see that, while they remain on my network (and thus display its SSID), they leave my router (192.168.1.254) and go to another router, 192.168.2.254. Btw, both routers have the same subnet mask.

Whenever they are on that other router (again, showing my network's SSID), I can log in to the other router because there is no password protecting it.

This router-switching is random it seems, though they all seem to prefer to go to the other router. I have tried renewing leases which sometimes sends the devices back to my router.

I have no idea who's router it is otherwise I'd have knocked on their door and told them to effing secure their network.

What can I do to force my devices to always stick to my network??

TIA
/p



switon
Dec 27, 2012, 03:23 PM
Hi pullman,

Short Answer: Switch to a different subnet, say 10.0.0.0/24.

Shorter Answer: Switch your subnet from 192.168.1.0/16 to 192.168.1.0/24.

Now let me ask, is the other router/wifi extending your subnet? Can you see their devices on the 192.168.2.0/24 subnet? Do you see their zeroconf (mDNS, Bonjour) broadcasts? If their router is unprotected, then why not reconfigure their router? (Okay, so maybe this is not the most "neighborly" thing to do, but...)

Regards,
Switon

lostless
Dec 27, 2012, 09:00 PM
It seems both routers have the exact same SSID. You need to change your SSID. If both have the same ssid, the devices has no idea what router to go to.

jared_kipe
Dec 28, 2012, 09:37 PM
There are two very possible scenarios here.

#1. Your hypothesis. That your devices are joining the wrong wireless network with an identical SSID.

This can be fixed by simply changing your SSID, and enabling encryption (so that your devices won't join the wrong one if someone is maliciously duplicating your SSID.
This could also be verified by using a wireless network sniffer like iStumbler. (to look for two different MAC addresses broadcasting your SSID)

#2. My hypothesis. You have a rogue DHCP server on your network and it is handing out a different subnet and presumably different gateway to any clients it answers. This hypothesis is backed up by the fact that sometimes you can 'renew DHCP lease' and get back into the subnet you are expecting.

This can be fixed by tracking down any devices that may be acting as a DHCP (wireless AP extender maybe?) and either disabling their DHCP or switching the primary router (the router you know about) to the same subnet (hopefully without overlapping client ranges).

Technically #1 and #2 could be slightly overlapping too. For example someone might be joining your network, and either accidentally, or maliciously, running a DHCP server and tricking your devices into their subnet.

EITHER WAY:
Make a new SSID, turn on 'WPA2 Personal' with a nice strong password. Slowly start switching devices over to the new network as needed and watch for the shenanigans to start again. At that point, either one of your devices is acting as a DHCP server, or someone is hardwired into your network doing stuff that I would assume is malicious.