No other ideas now. You may need to contact tp-link support directly via their support email

When I try to connect the modem to the desktop pc the internet speed greatly decrease. [/QUOTE] slow when connected to modem? where is the powerline adapters? it would be more clear if you draw a...

where did you download the tpPLC utility? do you mean you are going to turn off the power save mode?

will the house light turn off when the problem happens? usually it is caused by powerline interference, you may test them in one room to see whether the problem still happens

You have already updated the firmware successfully, it seems that the power extender firmware has two parts firmware, one is for powerline part, the other one is for wifi part, anyway, is the problem...

on the wifi settings page, you can check the little box "hide ssid" if there is an option