I've been having some issues with one location in our network of four PA9020 adapters.  It is connected to a TV box and although the green PL light is lit, and network speeds of 2-300 mbps on this adapter are shown in the Utility software, I'm getting severe break up on the TV box, and it is unwatchable.  Using a laptop, I determined real download speeds are between 2 and 7 megabits on this adapter - not enough for streaming HDTV reliably.  Via Wifi, or direct connection, or the other PLA's, the internet download speed is normally around 70 mbps.

Anyway, as part of the troubleshooting I attempted to enable "Lower PLC to VDSL Interference Mode" on all adapters via the utility software.  It did not improve matters, in fact it made them much worse (the problem adapter dropped off the network entirely).  However, I now can't switch this mode off.  Each time I change the switch to "Off" on each adapter, and each time the software says "Saved".  But the next time I go in, the mode has automatically been re-enabled.  This happens on all adapters - even the one directly connected to my PC.  I'm using the Windows TP_PLC Utility (dated 2020-11-27) and it otherwise seems to be working.  Please advise what is going on and how to turn off this mode?

Thank you