Need Advice on Cable Amp Install

Hello 

I researched the below critical error I'm getting on my modem due to noisy upstream cable issues. I have no splitter, attenuater, etc.

I'd like to install an active return cable amplifier, but there is only one cable coming into my house from the outside junction box. I thought for the amps, you have to have one power cable and one data cable, so I need help.

Here's my error:

No Ranging Response received - T3 time-out;CM-MAC= redacted;CMTS-MAC= redacted;CM-QOS=1.1;CM-VER=3.1;

Thanks!