For the Draytek ADSL1 modem/router units, which includes Vigor 2500/V/We, 2600/V/G/VG/Ge/plus:
All the Draytek models specified above support the G.DMT modulation (ADSL1 standard), so provided that the ADSL2/2+ ISP also supports G.DMT modulation, then the router unit should work. If the ADSL2/2+ provider does not support G.DMT modulation, then we cannot guarantee compliance on the ADSL2/2+ line.
We understand that most ADSL2/2+ providers support G.DMT modulation, so in most circumstances, your vigor ADSL1 modem/router should work without any issue.
If you are unsure of the modulation being used, please check with your ISP.