I activated the vpn on the new pc (as the death of the other) and the problem reappeared on both at the same time.
My computer is connected with a network cable directly to the box and the other by the wifi.
On mine, the vpn does not succeed to connect, except after restarting the pc and on the new one (there was the same problem on the old one), there are always disconnections.
I hope that these explanations are more clear ;-)
Thank you