Hi,
Since end June my ST546v6 reports Output Power (Up/Down) [dBm]: 12.5 / 21.5. And two exceptional days at 12.5 / 22.0.
Looking at kitz earlier comments "if your line has >19dBm output power then its reaching its limits" my line must be near the limit.
Other stats currently: Line Attenuation (Up/Down) [dB]: 20.5 / 37.5
SN Margin (Up/Down) [dB]: 9.5 / 11.0
Bandwidth (Up/Down) [kbps/kbps]: 735 / 6,676
Cheers,
Peter