Question My PC cannot reach speeds higher than 100 Mbps


Nov 19, 2014
So I have a 300 Mbps plan, and every device on my network can reach these speeds using

The steps I've taken up until now:
  1. Had my ISP install a new modem,
  2. bought a 4Gbps router (linked with a short 2ft, new cat5e cable),
  3. purchased a new Cat 6 cable that goes directly from the router to my PC. 4. I've connected the same ethernet to my Macbook pro and have gotten 350+ Mbps using a speedtest. I did this because it proves the modem, router, and ethernet are all providing the proper speed.
  4. I've made sure the Killer Network driver on my motherboard is updated.
  5. I've connected a PCIe wfii adapter, which is stated to be able to reach speeds of up to 1.3+ Gbps, but it is ALSO gets limited to 100-120 Mbps.
  6. I did a clean boot of my PC, by first disabling all services and disabling all startup services. Still throttled somehow.
Here is the ethernet status:

One thing I found peculiar was that I didn't have an option in the ethernet controller -> Speed & Duplex for more than 100 Mbps Full Duplex (though it was set to auto-negotiation)

I'm totally at a loss, I share my wifi with quite a few roommates, but it seems that my PC that is throttling me.
Some of 1Gbps nics also don't have an option for 1Gbps but 'auto' like what you see--perfectly normal since auto-negotiation is required for gigabit.

You've done a good job of checking a lot of the potential problems. Try booting a linux live cd/usb and see if your speeds are better there. If not, then it's probably a hardware issue.