Question Why is my internet speed stuck at 100Mbps

Nov 18, 2022
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Hey I've got an issue with my computer where my connection is capped to 100mbps on my pc wich was not the case before, This happoened yesterday after reinstalling windows and I did update my LAN driver. I did try aswell using the same cable that I use on this pc on another pc wich gets the actual connection I should be getting and I tried aswell forcing speed and duplex to a Gbps wich did not change it. I don't have a single clue what can be causing this because the cable is fine connection aswell but theres just something wrong on my pc somehow does anybody have a clue to what can be causing this problem ?
 
It is almost always a bad cable. You want to leave it on auto, if you set the pc to anything else the router/switch can get confused and there is no way on these devices to set the rate other than auto.

Your problem is you assume that a cable is fine because it works on another device. What is far more likely is the other device can tolerate a cable that is slightly out of spec more than you pc.

The speed setting is all done with hardware checking voltages etc, there is no real software involved so if it is not a bad cable it leave a bad port in the pc. That can't be fixed other than using a add in board. It is extremely rare to get a bad port in a machine.

The cost to test and maybe fix a cable almost never is worth it unless it is very long or it is in the wall where it is hard to replace. Your cheapest option is going to be to buy a new cable. Note there are massive amounts of fake cable being sold, which could also be your problem if the cable you have is not a actual ethernet cable.

You want cables that are pure copper (no CCA) and have wire size 22-24 (no of that flat or thin cable that is so common). You need nothing real special cat5e can easily do 1gbit but if you can get cat6 cheap that is fine also but it will not run any better or faster than cat5e.
 
Nov 18, 2022
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I left it on auto, and just tried out a different cable aswell but its still the same where my laptop gets the speed my connection gives but my pc still stuck on 100Mbps. On the image the laptop is the other pc and the big screen is my pc
 
So double check that it is set to auto.
Try a different port in the router.

.....Note I will assume this is a direct patch cable that does not connect to some kind of in wall cabling.

After this you have almost nothing left to try. You buy a PCIE or maybe a USB3 ethernet card. They are fairly inexpensive but it is still likely going to be cheaper to buy a new cable just to be 100% sure before you buy a new ethernet port. It is extremely rare to get a failure on the port unless you say physically damaged it.
 
Nov 18, 2022
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It is a direct cable that goes from my router to my pc and also changing port from my router doesn't change anything still same issue so I guess this brings us to the issue being the ethernet port on my pc but that's too weird all I did recently was flashing my bios to change cpu and then reinstall windows I don't see how could that impact my connection
 
You could I guess check the bios for any strange setting that might have changed. Sometimes so called green/power saver stuff causes issues but more it just doesn't work on long cables.
It is not likely drivers because if had for example did not load the motherboard chipset drivers the ethernet port would not even appear.

Again in almost all cases this is a cable.
 
Nov 18, 2022
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I don't really know how I could identify these weird settings, but I did try my pc on other cables and it was the same so I think my issue is the port on my motherboard
 

Cj-tech

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Jan 27, 2021
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I don't really know how I could identify these weird settings, but I did try my pc on other cables and it was the same so I think my issue is the port on my motherboard
Were you getting faster speeds before on the desktop? What motherboard do you have or is it a prebuilt? If you were getting the same speeds before, I would guess it’s a driver issue or a configuration issue. Is there anything in Device Manager with an exclamation mark (⚠) beside it?
 
Nov 18, 2022
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Yeah I should be getting the same speeds as the notebook gets on the picture posted earlier, i'm on a B450M gaming plus from msi. And no I don't have anything in device manager
 

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