Getting higher internet speeds on Windows and lower on hackintosh. How can I get the speed to be higher than 100Mbps? (Killer E2400 Gigabit Ethernet)

Hi all!

I recently started using my PC hardwired to my router and when I use Windows or Linux, I am getting speeds of up to 900-950 Mbps down and up. I have a Gigabit fibre connection.

When I use my my hack, I am limited to less than 100 down and up. I have checked the advanced settings in network preferences and it is set to automatic where the speed is listed as 100baseTX. I am able to select Manual under the hardware tab and changing the speed to 1000baseT makes the ethernet connection disconnect and connect over and over again. At which point I have to remove the service from the list of connections, add ethernet again and get back to less than 100Mbps speeds for ethernet to work again. Here are my specs:

CPU : Intel - Core i7-6700K 4GHz Quad-Core Processor Motherboard : MSI - Z170A-G45 GAMING ATX LGA1151 Motherboard Memory : G.Skill - Ripjaws V Series 16GB (2 x 8GB) DDR4-2400 Corsair Vengeance LPX (2x8GB) 3000mhz Memory Storage : ADATA - Premier SP550 120GB 2.5" Solid State Drive Storage : Seagate - Barracuda 1TB 3.5" 7200RPM Internal Hard Drive Video Card : MSI Radeon RX 580 Gaming X 8 GB Case : Corsair - SPEC-02 ATX Mid Tower Case Power Supply : EVGA - 750W 80+ Bronze Certified Semi-Modular ATX Power Supply 

I am using the latest AtherosE2200Ethernet kext that I got from the kext repo.

Is there a solution to this? How can I get higher speeds? At this point, I'm getting 200-300 Mbps with my WiFi and I'm bummed that only my hack is not able to get high speeds I should be getting with the ethernet cable..

Thanks for any help!