Shared IP problems!

Hey there,

I'm a complete newbie here, but my faith is in you guys. I have some serious network trouble going on here and no one in my neighborhood seems qualified to help me.

I have a brand new Airport Time Capsule 3TB at our house which sets up a new network apart from my original router, and that signal is being extended by some TP-Link extenders. Everything works fine, except for the fact that all our mac's (and sometimes even our iPhones and iPads at the house, although they recover much faster than the computers) seem to have trouble with connecting. I get the good old exclamation mark in the wifi image stating that there is 'another device using my IP address". Signal is fine, just can't connect due to this problem.

My technical thinking doesn't go any further than renewing the DHCP lease (which works, sometimes, very limited) and turn everything on and off again, which will get it all to work for a limited amount of time again. Is there something basic I can do about this? Nothing drives me more crazy than a malfunctioning wi-fi connection :')

Details:
Macs:
Macbook Pro 13" Retina OS X 10.9.3 (late 2013)
iMac 21,5" OSX 10.9.3 (late 2009)
iMac 20" OSX 10.5.7 (early 2008)

Mobile devices:
1 iPhone 4S, 1 iPhone 5, 2 iPhone 5S
1 iPad Air

ps- sorry if this is a FAQ *walks towards the corner of shame*

have you switched the wifi signal from your original router off?

That's a pretty good question. The only thing I did is connect the Airport Time Capsule to the original router with an ethernet cable, I didn't change anything on the original router. Could that cause problems? (I am such a noob when it comes to these kind of things..)

What's happening here, most likely, is that you have two routers trying to do the job of a router. Having both wifi networks on isn't going to cause this kind of issue.

Out of the box both routers are providing DHCP facilities - i.e. dishing out IP addresses on your network. It's like two people at the phone company giving people new phone numbers from the same list without talking to one another about who's got what.

You have several choices. But the easiest solution is to use Airport Utility to put your Time Capsule into 'bridge mode'. This way it takes it's own IP and behaviour from the existing router and the network world will be a happy place once more.

In the long term, you may wish to consider doing away with your original router and connecting the modem direct to the Time Capsule in 'full' router mode and let that manage the entire network.

I will try the bridge mode and see if it goes well - quite ironically my wifi has been pretty good since this morning when I posted this, so let's hope this will all be just fine. Thank you so much!

The issue will only occur when you get a device connecting through the old router and a device connecting through the Time Capsule.

This is more likely to occur when you have many active devices at the same time. But one way or another you can't have more than one DHCP server on a network unless they are using different ranges/subnets etc. But that's overkill from a home network. Using retiring the old router or putting the TC in bridge mode are the most practical approaches