By changing the cable and xDSL filter my one:; = 1 psc I stabilized my connection (over untimely synchronization loss several times a day and variable rate of 5 to 20 Mb / s VDSL) and reached my Maximum throughput VDSL2 45 Mb / s without any disconnection.
I recommend this RJ11 cable, the quality is at the rendezvous.