Interleaving/INP has a side effect of the max attainable being exaggerated.
If the (downstream) SNRM is around 9-10dB (rough calculation) then your brothers line is banded/capped by the DLM.
I saw he was on fast path as it was a line item in the BT smart hub interface. Must be DLM for him then.
I must have a much cleaner line, hopefully that won't change with the move to plusnet.
Do you know if DLM allows a 3dB SNRM on a clean line that is on a ECI cab?
My HH5 rebooted itself every 4-10 days (apparently its a thing with them) but the TP-Link is solid.