Hi Spiral, some suggestions below:
1. try to load the latest 19.3 driver package (win7 64bit) found in this site - https://downloadcenter.intel.com/Detail_Desc.aspx?DwnldID=18713
2. try to run the diagnostics test available in the adapter properties, link speed tab
3. in case you have cat6A cable, you may try it out
4. try to do back to back connection to another workstation for further isolation
hope this helps.