If only an existing VDSL modem must be replaced (in this example a Sphairon Speedlink 1113), then the modem should not even be configured - Plug'n'Play. VLAN tagging had previously been the router does.
Is used throughout with VDSL50 (Vectoring).
The modem was installed three months ago and since then runs smoothly without connection losses or crashes.
When used with vectoring, it is important that a suitable current firmware is installed by the manufacturer.
Under myvigoreu.draytek.com/download_de/Vigor130/ these available (eg in the telecom Vigor130 firmware V3.7.6 should english - Modem4 VDSL-Vectoring.zip function).
If no synchronization is possible at the DSLAM with vectoring, the modem supports ADSL2 + (18MBit / s) as a fallback - so it is also with the wrong firmware online anyway.