Question Ethernet cutting out at full duplex

nico1337xd

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Sep 1, 2018
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Hello, i've just built my new pc, a few days ago now. All drivers are installed and updated, same with bios. When im using ethernet connection at 1gbs windows thinks im plugging in and unplugging my LAN cable constantly. It connect and disconnects around 10 times per minute if not more. If I force my speed and duplex setting to 100mbs half duplex it starts working normally.

I've used same cable with another PC and it worked fine, 1000mbs/1gbs without any problem. Modem supports the speeds and my ISP is giving out 1000mbs up and download for sure since I've tried with my laptop and another desktop. Bought a new cable today to double check and same with both my CAT6 cables.

I've got a ASUS Rog Strix Z790-A motherboard and the Intel Ethernet Controller I226-V. I've thought of it being a driver issue but I can't find any older drivers for this ethernet controller. The one I have is driver version 1.1.3.28.

So basically, does anyone know what the problem might be and how to fix it?
 
Pretty much you need to really hope you have bad ethernet cables.

The speed negotiation is done at a hardware level and is not really any kind of driver of software.

This means you have a bad cable, a bad port in your router or a bad port in the pc. Unfortunately just because a cable works in other machines does not mean a lot. Cables that are marginal will work in some machine and not others. Also the 2.5g port is much more sensitive to cables out of spec.
A very large problem is all the fake ethernet cables on the market. Almost everything you find if you search amazon are those flat cables which have wire much too small to meet the certification standards for being ethernet cables. You only need cat5e cables but they must be pure copper with wire size 22-24 awg.
 

nico1337xd

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Sep 1, 2018
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Pretty much you need to really hope you have bad ethernet cables.

The speed negotiation is done at a hardware level and is not really any kind of driver of software.

This means you have a bad cable, a bad port in your router or a bad port in the pc. Unfortunately just because a cable works in other machines does not mean a lot. Cables that are marginal will work in some machine and not others. Also the 2.5g port is much more sensitive to cables out of spec.
A very large problem is all the fake ethernet cables on the market. Almost everything you find if you search amazon are those flat cables which have wire much too small to meet the certification standards for being ethernet cables. You only need cat5e cables but they must be pure copper with wire size 22-24 awg.
Allright ill go pick up a new another ethernet cable tomorrow and see what happens
 
Dec 3, 2022
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Probably a spotty connection.
Try with a new cable.

If the issue still continues, you can try widening the RJ45 connector of the cable with an electrical tape or something without covering the pins.

I have a marginal ethernet port on my laptop and it has the exact same issue.
I got away with it by widening the connector of the cable with an electrical tape.
 

nico1337xd

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Sep 1, 2018
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Probably a spotty connection.
Try with a new cable.

If the issue still continues, you can try widening the RJ45 connector of the cable with an electrical tape or something without covering the pins.

I have a marginal ethernet port on my laptop and it has the exact same issue.
I got away with it by widening the connector of the cable with an electrical tape.
Do you mean putting the electrical tape on the sides of the connector to make it fit more exactly into the middle?
 
Dec 3, 2022
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Do you mean putting the electrical tape on the sides of the connector to make it fit more exactly into the middle?
It's not a permanent solution but it will help the connector to stay more firmly on the port.

Try wrapping the connector with tape.
Something like this:

 

nico1337xd

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Sep 1, 2018
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It's not a permanent solution but it will help the connector to stay more firmly on the port.

Try wrapping the connector with tape.
Something like this:

New cable didn't solve the issue so I dug out an old usb-c to ethernet adapter and I'm now using that with full 1gbps so problem solved I guess. I also tried taping without any luck. But for now I'm fine with the adapter.
 
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Although you likely will find nothing I would inspect the lan port and see if there is anything that looks bent or maybe there is some dirt or something in the port.

The ethernet ports though do actually fail it is just very rare. Since it is a 790 board it has to still be under warranty but RMA is such a pain.
 
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nico1337xd

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Sep 1, 2018
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Although you likely will find nothing I would inspect the lan port and see if there is anything that looks bent or maybe there is some dirt or something in the port.

The ethernet ports though do actually fail it is just very rare. Since it is a 790 board it has to still be under warranty but RMA is such a pain.
Port looks good, exactly like all other ports I've seen. But for now im happy.
 

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