1 adapter connected on one side to the terminal Airport Extrem, well systematically ADSL was cut? (As if it were the central or down, or outright failure ADSL).
Can not operate the system.
That finally worked when I spent the DHCP server function to the terminal Apple Extrem (so that it is no longer the Livebox that distributes IP addresses and Apple Extrem in "bridge") and there to the suddenly it worked, over ADSL outage.
Vertigo and misunderstanding anyway ... I have not found any history on the Internet face this very very special problem.
Last, one of the indicator (the right one) is supposed to flash ... well not with me, ever ... but it works. So more stress.