100MBps instead of 1000MBps (ethernet)

recently I bought a netgear PL1000 ethernet adapter. It has a maximum download speed of 1000MBps. However my computer only uses 100MB. I have a Gigabit Ethernet Controller so that souldn’t be a problem. Also my router sends 1000MB so thats not the problem either. Can there be a maximum downloadspeed of my ethernetcables or powerline? If so please let me know.