IP address allocation

Turbo-G

Turbo-G

Turbo-G

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Joined
6 Jan 2009
Posts
1,191
Hi all,

Having a few problems with my home network, wondered if you could assist please?!

I have an old Sagem Sky BB wi-fi router, with wifi disabled (acting as an ADSL modem), connected via ethernet to an Apple airport extreme base station. From here I then have an ethernet cable going to a D-Link ethernet over power adaptor.

Upstairs, connected to the D-Link adapter via ethernet is my iMac. The Apple AEBS is also transmitting a dual frequency wifi network too.

I have no issues with my wifi connectivity, but every so often (quite frequently at times) my iMac will randomly lose its wired internet connection. On inspection of the network settings, I will then see a none internet facing IP address, e.g. 169.254.xxx.xx. If I click to renew the DHCP lease, a 192.xxx.xx.xx address generally comes back and all is OK. Sometimes I have to turn the D-Link adapter on/off. Other times I turn off/on the Sky modem too... The wifi network is fine throughout by the way...

Am I right in thinking that the modem is failing to allocate an IP address, or would it be the AEBS? If its the modem at fault, I guess I should look at replacing it with a proper modem. Or could it even be the D-Link adapters playing up somehow?

Thanks in advance!
 
Only one device should be doing DHCP - if you have two doing it this could be the issue.
 
The old BB router should have WiFi and DHCP disabled at minimum.

If only 1 is serving DHCP then there is no reason why you would have to assign a static IP. Seeing as the wireless is fine it seems more likely that the powerline adapters are playing up when your iMac is looking to renew it's DHCP lease and it times out, leaving you with a 169 address.
 
Ok, thanks for the assistance thus far. Turns out my Sky modem/router is has DHCP enabled, and my AEBS was set to DHCP disabled - bridge only.

If I turn off DHCP on my sky router, and switch DHCP only on my AEBS, entering the same IP range as shown on the sky router - 192.168.0.2 to .254, I get an error from the AEBS stating that:

"sharing a range of IP addresses using only DHCP only requires manually configuring your WAN IP address. If your ISP gives you a range of static IP addresses you should manually configure your base station with the first IP address, and distribute the rest via DHCP".

Any thoughts what I'm doing wrong here?

Cheers
 
Your DHCP pool is also slightly off, as you need to take into an account the IP address for the AEBS and also the powerline. This might be causing the IP clashes.

So for example:

BB router: 192.168.0.1 (Static)
AEBS: 192.168.0.2 (Static)
Powerline: 192.168.0.3 (Static)

DHCP range: 192.168.0.10 - 254

Hope that helps.
 
Sorry to resurrect the thread, I'm still having issues.

As you suggested Kaka, I have changed the DHCP range on the AEBS to 192.168.0.10 - 192.168.0.254, and now get "The value for "Range Beginning" is invalid.

This is a right pain. With regards to the Sky modem/router I have turned off DHCP and wifi access point. Is there anything else I need to do?

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