This thing is amazing! I replaced an old 12 foot coax cable (3-5+ years old?) for my cable modem and it drastically improved signal levels (SNR & power) and reduced correctables/uncorrectables down to 0! The old coax cable had corrosion and other junk in the connectors. I recommend that folks replace their old coaxial cables with newer decent ones like this $8 Amazon Basics to see if that helps with troubleshooting. My connection and download speeds are now very consistent (~90 Mbps down via speed test, rated at 75 Mbps down speed tier package) and the "Middle Variance" from testmy.net dropped from 80%-120% down to 0%.
The only criticism I have is what others have mentioned, the clear plastic protectors on the cable ends are difficult to remove.