Let me get this straight. You originally setup your Master server as the primary system to get the time from with "server 127.0.0.1". Then had the 4 slave systems get time from that.
Now, you changed the Master server to be an intermediary to an outside server "server canon.inria.fr". And your now saying that everything is fine except for the clients time is not keeping up with the new configuration.
Your stratum configuration is normal. Because you are connecting the former master to a new stratum 1 server. It is now a stratum 2 and the 4 are now stratum 3.
You probably need to make the former master and 4 slaves into PEERS so that they will be on the same level and the clients will become stratum 3. But, only have the clients get their time from the 4 systems that were slaves.
Here is a link that I think will explain a great deal.
http://docs.hp.com/cgi-bin/fsearch/f...0020528-125842