I hope you all do not mind that I reopen this topic. Was there a solution the problem found? If yes, what turned out to be the solution?
We have a similar problem as DirtyLarry has on our office network. It took us quite a long time to figure out the problem was related to an iPhone connecting to the network. (not just wifi goes down, LAN aswell)
The problem is that our internet service interupts (sometimes up to multiple times per hour), so at first we had a long diagnostic track by our ISP-company. Early on it was already clear that the modem/router started to reboot, but at first the phoneline was blaimed. Interference on the phoneline would cause the ADSL modem to reset itself if the interference would get to high. It took quite some time to trace the problem to the WiFi Access point, but finally it was clear the Access point causes the modem/router to reboot, thus loosing all internet connections.
With the accesspoint taken offline the problems were over (wifi on the modem/router has been disabled). No Wifi connection were available at that point. After some more days of making sure the connection was stable now, we started one by one connecting devices to the network by wifi, by starting with the AP without any connections, each with enough time in between to make sure connection remained stable (approx 4 hours between each device, 2 per day).
Finaly it turned out the network crashed with the connection of an iPhone. It took no longer than 5 minutes for the network to fail after the iPhone connected.
At first we blaimed the AP (D-Link DAP2553): probably it had something to do with the communication between this D-Link and the iPhone, since the D-Link was a relatively new addition to our network (approx 8 months). We have had this network running for 3 years without any problem and also with iPhones connected thtough WiFi with no problems so we figured the newest addition would cause the conflict. But after replacing the D-Link with our old Linksys WAP54G the problem remained: with the iPhone being able to make a connection to the wireless network the router reboots itself at any given time. At the moment we are trying Wifi through a Linksys WAP-610N AP and still the same issues when a iphone is connected.
So now, three months after our initial problems started (we can specificly date this problem: it started on July 12th. Before that time we had a sporadic drop in connection, but starting that thursday our connection was higly erratic) we finaly know for sure the problem is the (either, we have 3 in our network) iphone and not the Ap, router or any other Wifi devices.
Some data about our network setup.
- ADSL connection through modem/router, which runs 1 UTP to a switch from were LAN connections are dived over our offices. Through a wall outlet we have connected an AP through LAN.
- SSID is broadcasting and unique on a channel that is not used. We have tried different SSID's, same problem.
- Wifi security is WPA2 (personall)
- Modem/Router is DHCP server in internal range (192.168.1.xxx)
- 2 of the 3 iphones are Iphone 4S's, that run on iOS 5.1. The 3rd iphone is an older iphone 3, do not know the iOS version but am fairly sure the connection also drops by connection just this iPhone.
- Currently I have MAC-filtering enabled on the AP to make sure the Iphones cannot connect, even if they have the password for the wifi network (only started using this about 1 month ago, so this is not the problem)
- The IP addresses of most devices are not static. But my administrator-page of the modem/router shows the device connected, their MAC addresses and their IP's, so I am sure there are no duplicated. Also my virusscan/firewall program (Eset Smart Security) pops up a warning if duplicate IP addresses are present in the network. We have had that happen with a Samsung phone, but this never had causes a disruption of the entire network.
- We are able to repeat the problem over and over. Just have the iphone connect and wait an hour. Additional remark what we have noticed this morning but it may be nothing: with 1 iphone 4S on the wifi network and placing it on the desk-charger, the internet connection of the network dropped. Placing it at the charger again, again caused the connection to drop. This requires further testing. But we had also a connection dropped when the iphone received a whatsapp message, or just by plain doing nothing (that we can see at least). When connecting, everything appears fine, connection does not drop at that instance...
- DCHP lease (checked on my desktop) was given this morning when booting up and expires just under 26 years from now (!). Not a problem here I would assume, since all computers are powered down in the evening and the cellphones return home with their owners so get disconnected aswell.
On my desktop terminal (LAN connection) I have the program "servers alive" running continuously (starting after we learned the problem was with the AP and not the ISP, so this is not the cause) which I have setup to ping three different website, our ISP's DNS-IP and the standard local gateway (modem/router). This way I monitor the connection and get notified when connection is lost. I have it set up to send 5 ping packages every 10sec to the different IP-addresses. This is what I have learned so far:
When I get notice connection is down (pings do not reach a remote website's IP), all other checks turn 'red' aswell. (3 websites and the DNS). The ping to the gateway IP stays active. I have not timed this exaclty but after approx 20 seconds the gateway ping turns 'red' also (ping to gateway fails). After this it takes somewhere between 1 and 2 minutes for the ping to gateway to succeed again (in this time the modem is rebooting, I have checked, and thus not able to return a ping request). After the gateway turn 'green' again in the checkprogram, it takes approx 15 seconds for all other websites are 'green' again, mening the connection to the internet is up again (all times mentioned above are approximate, since ping-command are send every 10 seconds).
So far, we have not come closer to a solution yet. We hope you all have, since no further remarks were made on this thread. Usualy this means the problem was resolved.