Another computer using IP address -again

Question

Hi,
I have had to reset my network due to electrical work being done on the house. I am using an AirPort Extreme 802.11n 3rd gen at the base and a second AirPort Extreme 802.11n 5th gen to extend the range of the network.
When I called my service provider, Bell, they had me enter an IP address to establish the modem connection. I entered it on my laptop and not the the main computer (iMac) which is the one the network was initially set up with.
After that, with apple support, I was able to set up a new network using an AirPort Extreme 802.11n 3rd gen at the base and a second AirPort Extreme 802.11n 5th gen to extend the range of the network. Since then when I would use the iMac I was told 'another computer is using same IP address'. sometimes the internet would still connect. Sometimes when I would use my laptop I got the same message. None of the other computers or iPads have been affected.
After connecting the iMac directly to the base AP Extreme by ethernet and then disconnecting the ethernet net and restarting the computer, the iMac connects with the network. right now the iMac IP is 192.168.2.11.
While sitting in the same room as the Extreme base station I was able to go online with my laptop -macbook pro- and the IP address was 192.168.2.24
I then closed the cover on the laptop and went into another room about 15 ft away and I was unable to go online when the computer awoke as 'another computer is using same IP address' and my IP address on the laptop had changed to 192.168.2.13.
I restarted the same laptop and when it opened the first message was 'another computer is using same IP address' 192.168.2.13
When I went to apple support this time I was told that I would have to pay for support as opposed to my call of last week. That is why I have not called them yet. Hopefully someone can help me get things back to normal.
Thanks in advance
Kim

Answer 1

the Router Mode : Off (Bridge Mode)
Thanks for the checking that.
This setting confirms that it is your Bell modem/router that is in charge of providing IP addresses for every device on your network.
In Bridge Mode, the AirPort Extreme might be providing a wireless network signal, but it does nothing active as far as providing IP addresses to devices on the netowrk. The AirPort Extreme simply passes through the IP address settings that it receives from the Bell modem/router.
For some reason, the Bell modem/router is having problems keeping track of the IP addresses that it is assigning to devices on the network. I cannot say why.
Sometimes, an issue like this will go away if you power off the entire network....in any order that you want. Wait a minute, then start the Bell modem/router and let it run a full minute by itself. Start the AirPort Extreme next the same way. Keep starting other devices one at a time about a minute apart until the entire network is up and running.
This simple reset will give the Bell modem/router a fresh start to get things straightened out. If you continue to see the same problems, then you have to go to the cause of the problem..the Bell modem/router. Perhaps a replacement may be required.
If you need to call your Internet Service Provider, you now have the information that you need. Unfortunately, ISPs tend to try to find a way to place the blame on any problem on any product other than their own, so you might expect to hear some creative things from them.