Question Ethernet Cable Connection Capped at 100mbps


Dec 16, 2017
I'm trully stumped on this one.

I recently upgraded my ISP plan to 200mbps, and my PC has not been getting those speeds, staying at the usual 100mbps.
I called in the ISP tech support, and in doing several tests, here's what we found out:

  • Wi-fi works on 200mbps. It works on my notebook, cellphone and it works on my PC once I use a wi-fi adapter I have.
  • When connecting my notebook through a small ethernet cable I have on hand, it works on 200mbps (it´s a cat 5e)
  • My ps4 also gets 200mbps, same cable.
  • When I connected my notebook to the ethernet cable that goes from the modem to my pc (the modem is in the living room, so the cable goes through a pathway that leads to another room where my PC is at) it also had the speed capped at 100mbps.
So, naturally, I assumed the problem was the cable. I got a brand new cat 6 cable, just plugged it in directly to the modem, and the problem persists, even when I plug it into my notebook, so I know it's not my PC's network adapter (Intel I219-V) . Curiously, while the down speed stays the same, the upload speed is now 100mbps when it was previously 50mbps as is customary for a 100mbps plan. I've downloaded the most recent drivers from intel (it also came with one utility that confirms it to be capped at 100mbps, saying the linking partnet does not support higher speeds).

The only conclusions I can draw from this is that either the problem is the cable length (it's an 8 meters one that goes from my living room to the PC) which is a ludicrous one as I really don't think that kind of length can be a problem, or the Modem (it's the standard provided by my ISP) is somehow to blame even though it works fine with the shorter cable.

Does anyone here know what might be going on? Thanks in advance.
Could still be the cable, or it could be something with the drivers in windows for the nic. And here's how we figure it out...

Boot a linux live cd/usb and check the speeds there. I expect it to be the full 200. If it is, it's a windows issue and cable and nic are fine. If it is not, then could still be the nic or cable, but I'd be leaning towards the cable since there is a lot of fake and garbage cable out there. I'd buy a cable locally if the cable becomes the suspect, and then try the linux test again. If it passes, then you can check it in windows.

I really need to make a flowchart for this diagnostic process...
Does the cable run directly or are you using some in wall cabling also. It could be wall jack issues if they are in the path.

You should be able to go 100 meters with ethernet cables so distance is not a problem in your normal size house.

Now if you bought that flat cable that does have massive issues going any distance. That type of cable has wires that are too small to meet the ethernet standard so no matter what the manufacture says it is not a ethernet cable. You need cat5e or better if cheaper but the key things to look for is pure copper wire (no cca) and wire size 22-24. Do not buy any cables that the manufacture does not state this information and should also be printed on the side of the cable.