You have a few options, listed in order of complexity and setup requirements:
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[]Disable DHCP on your DLINK ADSL modem and use Fog as your DHCP server. The config is really easy if you just need it to give out adresses to a small network.
[]Disable DHCP on your DLINK ADSL modem and use a spare computer running Ubuntu as a dedicated DHCP server.
[*]Leave DHCP running on your DLINK ADSL modem and configure your Fog server to use LTSP/ProxyDHCP so it answers PXE boot requests with next server and file name options, but doesn’t handle giving out IP addresses.
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