So DSLstats is reporting the line attenuation. To the best of my knowledge, signal attenuation isn't available directly from the CLI with VDSL2, and if you enable the option in "Items to Monitor", it will report "Not available on VDSL2". However it's possible that the GUI is reporting signal attenuation, which might explain the difference.
You can check what the CLI is reporting by looking at Telnet Data --> Stats. About a dozen lines down from the top on my system there's a line which simply says "Attn:" and as far as I know, this is line attenuation. If the CLI in your modem reports it differently perhaps you could let me know.
By the way, both line and signal attenuation are reported in the pbParams output (see that tab under "Telnet Data") but they're reported per band here, and not overall.