After the pusher column Telekom has given me, that I agree with either an IP conversion or the contracts are terminated me I had my 3370 connected directly without a splitter.
This cable works to absolutely flawless!
Tip: if it does not work right away, let's see if there is an update for the Fritz box. After importing the version 6.20 VDSL works without splitter even before the analogue switch-off.