Yeah I did ask Zyxel support team enquired why is it disabled on G.Vector? They should fix it with next firmware but they say it end of life now, no further firmware now. Sound like the only way is openreach gfast modem that will enabled both G.INP and G.Vector because it will added extra 33Mbps on it.
I checking via DSLStats and found G.Vector as it marked all 4 does it mean enabled or not from my router?
xdslctl info --pbParams
xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason: 1
Last initialization procedure status: 0
Max: Upstream rate = 31288 Kbps, Downstream rate = 210563 Kbps
Bearer: 0, Upstream rate = 31387 Kbps, Downstream rate = 210988 Kbps
Discovery Phase (Initial) Band Plan
US: (348,1265) Gfactor=4
DS: (342,1166) Gfactor=4
Medley Phase (Final) Band Plan
US: (348,1265) Gfactor=4
DS: (342,1102) Gfactor=4