Why can't I get an IP address when switching access points until I reset the DHCP server

Question

I read the article How can I get the same SSID for multiple access points? which is exactly how I set up my network.

My main router with built in wifi, functions as DHCP server, then I have 2 additions wifi routers configured as access points, they do not function as dhcp servers.

All 3 wifi devices share the same SSID and have the same security setup. 1 of the 2 additional access point is connected by a standard network cable to the dhcp server, the other one first goes through a powerline before it goes to the router (no other devices use powerlines in my network, I had to do this to cover the distance in the backyard).

Now here is the issue, if I take my tablet for instance, and connect to the wifi and then walk to the garden it will not get a IP address from that accesspoint until I reset the dhcp server (switch off and on) then it works. If I then walk back into the house, it switches accesspoint without issues. I tried by switching the accesspoints around, but with the exact same outcome. I also tried by switching to different SSIDs, but still, I need to reset the dhcp server when I want to use wifi in the garden with a device that was previously connected to one of the other accesspoints.

I have no idea how I can solve this, does any have experience with those powerlines. Do I need a specific set of routers. Currently I use Linksys EA4500 as dhcp server, 1 linksys E2000 as wireless accesspoint and another Linksys WRT320N as Wireless accespoint.

Answer 1

From what I understand of your question, you're saying the problematic AP is the one connected via powerline network adapters (officially known as HomePlug bridges).

In my own experience, this simply doesn't work. You will find that connecting a device (e.g. a laptop) to the powerline adapter works fine. You will find replacing the powerline adapters with a long network cable also works fine.

Interestingly, there are products that integrate powerline adapters with a wireless AP. I'd recommend using a product like one of these instead.

Answer 2

Got my new router and after setting it up I did some testing. I set the distant powerline with the garden AP up in a nearby socket, so I could easily bypass the powerline and connect the AP directly into the router.

I was surprised to see that my tablet immediately connected wireless to the AP behind the powerline and I could access the internet. (I gave that powerline a different SSID so I would know to which wireless AP I connected). So I switched to another wireless AP and got immediately an IP address as I suspected. The ones that were directly connected with cable never gave me any issues. Then when I switched back to the AP behind the powerlines the issue occurred again, just as before, the message 'obtaining IP address' stayed fixed until the tablet got tired of it and tried to connect to another wireless AP.

I could switch back to any other AP successfully, but the one behind powerlines doesn't want to work anymore. I reset the dhcp server, and indeed, it allowed me to connect again to the wireless AP behind the powerlines. tried another AP again with success but when going back to the one behind powerlines, I no longer received an IP. I removed the powerlines, connected that AP directly to the dhcp server, tried switching between the 3 wireless accesspoints and this worked like a charm.

As a sidenote, the issue only occurs when connecting wireless, If I would use a laptop and connnect with cable via the AP behind the powerlines, this always worked and the AP can also be accessed via a browser from anywhere in the network at all times. Just Wifi does not seem to work consistently when you pass through powerlines to the DHCP server. Booo! for that. I'll have to invest in putting a cable in the ground now ...