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DHCP and static IP addresses

Posted: Wed Aug 10, 2011 12:49 pm
by Andrewski22
Just bought a 7800N last week on on the whole very happy with it but have had a few problems with it that I hope someone can help with.

My set up is the 7800N connected to my phone line downstairs in the house. The 7800 is then connected via ethernet to a homeplug. I have another homeplug at the top of the house to which I am connecting by ethernet cable to an iMac. I have updated the firmware to the latest UK version (1.06d).

Everything seemed fine when I set up the 7800 initially but I am finding that every so often the iMac will lose connection via DHCP and when the lease is renewed the imac gets assigned a 169 IP address. Switching from ethernet to wifi on the imac allows me to restablish connection to the internet (so I know that the 7800 has not lost it's connection) and eventually usually after a few hours I will be able to re-establish a DHCP connection via ethernet.

I have seen online that there are some issues with the DHCP lease on the 7800N so tried to establish a static IP address for the imac to avoid this issue using the MAC code of the imac. I set this up with an IP address outside the range of the router e.g. and when I connect the imac all the settings appear correctly but I cannot connect to the internet. Again when I return to wifi the imac gets an IP address from the DHCP and works fine.

Can anyone suggest what I am doing wrong? Do you think I would be better going back to the previous firmware?

Re: DHCP and static IP addresses

Posted: Wed Aug 10, 2011 9:14 pm
by Tomken
If you would like to visit there is an article written by Fred Sheehan which may be of help to you.

It's entitled "Possible workaround to get Bonjour Devices working with non Apple routers" dated 3rd Aug 2011 - don't know how to assign the URLs for these links, but you can "guest" and use the search facility - just enter his name and part of the title.

Hope this helps.

Re: DHCP and static IP addresses

Posted: Wed Aug 10, 2011 10:32 pm
by Tomken
Just had a word with Fred, he's had a look, didn't register to post but PM'd me with this.

Ok, just had a quick look but am not a member to post!

his issue is not the static IP address per se, it is the set up of this.

if the router uses 192,168.1.1 as its address, then the DHCP pool will be 253 hosts from -

If I want 3 static IP's for my home network, then I do 2 things, reduce the DHCP pool from 253 to 250 (maximum number in pool less the number of static IP's I want to assign) and set the DHCP pool to start at - and this then means I can set the Mac up with a address and this will not conflict or ever try to be issued via DHCP, i.e. they are taken out of the DHCP pool, so cannot be dynamically assigned. This should sort out his issue.

setting a high IP I think it was, is the wrong way to acheive his aim, as every time the Mac trieds to connect that IP will still be in the DHCP pool and so it will not be avialble,.

meant to say in the other PM, he 'may' have to change his default gateway on the Mac too to the routers IP for it to find the internet properly

Think this will be better than my previous attempt to help :)