Currently I am using MikroTik PWR-LINE Pro at my home. I have a 300Mbps internet but when I use these PWR-LINE Pro I can only achieve about 60Mbps. Is there any way to get it to full speed as I read in the specification that this device support up to 600Mbps passthrough speed. Thanks.
Pwr-line devices are much like wifi: they have theoretical maximum speed which is almost never achievable. Actual speed depends very much on actual electrical wiring, fuse type and placement, star alignment, etc. My (limited) experience says your actual result (60 Mbps) is not that bad.