Is your PC and/or network capable of speeds in excess of 100 Mbps?
Does your PC have a gigabyte Ethernet adapter?
Before checking your speed using Internet speed tests run test using LAN speed test to confirm your PC, router and cables are capable of the Internet speeds you are paying for. If you can't get speeds in excess of 165 Mbps on your LAN then you will never get the speed on the WAN when running a speed test. What you will get or have is the capacity instead is the ability to have multiple 50+ Mbps connections.