These are quite important stats:-
6. Data rate: 799 / 4200
7. Maximum data rate: 9050 / 62460
8. Noise margin: 23.8 / 34.2
9. Line attenuation: 0.0 / 22.6
10. Signal attenuation: 0.0 / 21.1
As VDSL connections use a number of bands, it appears that US attenuation is never reported in the 'single' overall value.
(this is from my connection):-
Down Up
SNR (dB): 5.1 6.1
Attn(dB): 24.5 0.0
Pwr(dBm): 12.7 6.6
However, this is the 'per band' data for my connection:-
xdslcmd info --pbParams
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Last initialization procedure status: 0
Max: Upstream rate = 4851 Kbps, Downstream rate = 21880 Kbps
Bearer: 0, Upstream rate = 4877 Kbps, Downstream rate = 20695 Kbps
Discovery Phase (Initial) Band Plan
US: (7,32) (871,1205) (1972,2782)
DS: (33,859) (1216,1961) (2793,3970)
Medley Phase (Final) Band Plan
US: (7,32) (871,1200)
DS: (33,859) (1216,1846)
VDSL Port Details Upstream Downstream
Attainable Net Data Rate: 4851 kbps 21880 kbps
Actual Aggregate Tx Power: 6.6 dBm 12.7 dBm
====================================================================================
VDSL Band Status U0 U1 U2 U3 U4 D1 D2 D3
Line Attenuation(dB): 8.1 53.5 N/A N/A N/A 21.7 65.7 N/A
Signal Attenuation(dB): 8.1 52.4 N/A N/A N/A 30.5 65.4 N/A
SNR Margin(dB): 5.9 6.1 N/A N/A N/A 5.1 5.1 N/A
TX Power(dBm): -0.8 5.9 N/A N/A N/A 11.7 5.9 N/A
A HG612 would provide more detail per band, such as DS & US Line/Signal attenuation, SNR per band etc., but the significant details in your stats are the high Noise Margin values & attainable rates (Maximum data rates).
Such high values suggest that much higher sync speeds should be achievable (e.g. as shown in the Maximum data rate values).
However, it appears that DLM has taken action to compenstate for whatever is causing 'interference' & has capped your connection to ridiculously low sync speeds of 0.8 Mbps US & 4.2 Mbps DS.
Until you are able to monitor via an unlocked HG612 it may be worth checking your stats at different times of day/night.
You may then be able to detect patterns of vastly reduced Noise margins etc., suggesting a REIN or HR (High Resistance) issue, either with a regular pattern or completely intermittent.
It does appear that the onus is now on yourself to 'prove' there is still a fault.