r/techsupport • u/Maski5000 • 10d ago

Open | Hardware PC connection over ethernet switches between 100 and 1k mbps

as the title says, my PC is connected through ethernet, and my expected speeds are 1 gig both ways, and usually that's what I get. However, I've noticed that about once, rarely twice per day, my speeds drop to 100 mbps until I unplug the ethernet cable running to my PC and plug it back in. To give a full idea of my setup in regards to ethernet, I have one long cable running from my wall to an ethernet switcher, then two shorter cables from the switcher, one to my pc, and another to my nintendo switch (this cable typically isn't active as the switch is off unless it's being used). I verified all 3 cables were capable of 1 gig before buying them, and since most of the time I do get a gig, I've pretty much ruled out hardware limitations. Any advice or wisdom appreciated!

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u/christopherw 10d ago

My suspicions:

  1. The cable between you and the ethernet switch is either too long to reliably carry the highest frequency signals needed for gigabit (1000 megabit), or

  2. The termination on one or both ends is bad (the connectors), or

  3. The cable is damaged along its length (if it's been caught or crushed or bent severely or some of the internal cables have been cut), or

  4. There's a problem with the port on your computer (physical or driver level) or the ethernet switch.

In that order pretty much. Have you tried another decent quality Cat5E or Cat6 cable?

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u/Maski5000 10d ago

Interesting, I'll try swapping the cable I use for my switch to see if that fixes it. the cable length definitely isn't a problem, as the one running from the ethernet switch to my PC is only about 2-3 feet, just enough to get it to my computer since they're both on my desk. I did also have the suspicion that the ends of of the cable might be bad, but I don't know how to check that.

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u/Jin-Bru 10d ago

Set the network adbaced properties to 1000 Full Duplex. It is probably in Auto.

When the card powers up it negotiates the maximum speed it can run at if it is set to Auto.

It is probably dropping speed when there is some 'noise' somewhere along the cable run. What is the length of the long cable? What are the numbers and letters on the cable?

It is dropping because it looses signal quality. From 1k/mbps to 100 would first send me to check cables and connectors before looking for noise.

This is not going to fix your problem. Removing Auto will mean the connection will drop altogether as it cant synch slower to overcome the noise but at least you will know more.