Hi, We have 2x SmartNode 4114's = a total of 8 FXO ports. United States. I've tried all kinds of settings to remove/reduce the echo. My current best is running G.168, Non-Linear Adaptive Processing mode 9 (are these dB's?) with -4 dB output gain. I notice the smartnodes have no way of specifying impedience in reistance or microfarads. Is this correct? Is there anything else I can do??