I suspect you really have cat5E cable. Just like cat 3 cable it is rare to find anyone who actually makes it anymore since the cost to make even cat6 cable is almost the same.
Cat5e will do gig but from what I read the ethernet port on this device is only 10/100 so the port will limit you no matter how fancy a cable is. Why they say 270m and then not put in a gig ethernet is probably a more relevant question.
I thought MoCA devices are capable of 270 Mbps. Why are the units shipped with Cat5 cables, which is only capable of 100 Mbps. Are the Moca devices capable of 100 Mbps on the ethnernet side or the wrong cables shipped with the units???