Question Problems with Ethernet adapter

Jul 20, 2020
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Hello!

I'm having a problem with a cable WiFi in my house. I recently bought a new WiFi Router, a TPLink Archer C50. Before that, I was using an old NETGEAR WGR614.

I connected the C50 to my modem and configured the WiFi, as well as the Ethernet cable. Before that, the NETGEAR was also being used both as a cable router and WiFi Router with no problem.

However, when I tried to connect the C50 to my desktop computer through the ethernet cable, the computer refused to acknowledge the new network, first, showing an error that the cable may be broken. I used the cable on a laptop computer and it worked perfectly. The computer started to connect and disconnect the network intermittently. I followed some guides regarding that, including changing the Speed & Duplex value to 10mb Full Duplex, disabling the Energy Efficient and Wake on Magic Packet, to no avail. The computer keeps showing that it's connecting and disconnecting.

However, when I plug the cable from the C50 to the NETGEAR router, and the router to my computer, it works completely fine. I need some help in identifying the error and fixing it, so that I don't need to use the NETGEAR router as a "middleman".
 
First, the TPLink has 4 LAN ports ... does the same problem happen on all 4 (could one of the ports be bad)?

Second, check the Ethernet port on your computer for dust or lint or anything that would be causing poor contact (uncommon unless you have not used the Ethernet port for a while).

Third, try a different cable (you may have done this already).
 
Jul 20, 2020
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First, the TPLink has 4 LAN ports ... does the same problem happen on all 4 (could one of the ports be bad)?
I have, unfortunately. The same error occurred.

Second, check the Ethernet port on your computer for dust or lint or anything that would be causing poor contact (uncommon unless you have not used the Ethernet port for a while).
It's clean, when I use it with the NETGEAR router it works perfectly fine.

Third, try a different cable (you may have done this already).
I'm using a different cable with the NETGEAR router. The problem doesn't seem to be in the hardware, but in the software. Thanks for your help!
 
I'm using a different cable with the NETGEAR router. The problem doesn't seem to be in the hardware, but in the software. Thanks for your help!
When you move the cable from TPlink to the Netgear, the software does not change. If anything, you have a hardware incompatibility between the 2 devices (your PC and the TPLink). To me, that seems weird, but I have heard others have a similar issue. They have found that only by having a device in the middle do they get constant connection. I don't know why. It shouldn't happen, but it does. Yes, it could be a setting on one device or the other causing it, but I don't know what that setting would be.
 
Jul 20, 2020
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When you move the cable from TPlink to the Netgear, the software does not change. If anything, you have a hardware incompatibility between the 2 devices (your PC and the TPLink). To me, that seems weird, but I have heard others have a similar issue. They have found that only by having a device in the middle do they get constant connection. I don't know why. It shouldn't happen, but it does. Yes, it could be a setting on one device or the other causing it, but I don't know what that setting would be.

Yeah, it looks like it. I just made a full reset of the computer and the problem still persists. The only thing is that the conenction is unstable as well; the same problem happens in larger intervals. It disconnects and shows the "Ethernet doesn't have a valid IP cofiguration" and then returns.

I have a Realtek PCI GbE Family Controller, if that helps. Maybe it's something related to the configuration of the ethernet adapter on the motherboard? My motherboard is an ASUS PRIME B450-GAMING/BR, if that helps.
 
Jul 20, 2020
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UPDATE: I tried to connect to the modem directly, and the "Ethernet doesn't have a valid IP cofiguration" error persists. I have no idea what it means.
 
UPDATE: I tried to connect to the modem directly, and the "Ethernet doesn't have a valid IP cofiguration" error persists. I have no idea what it means.
Probably should have mentioned this ... if you are going to run the Netgear in the middle, only use the 4 LAN ports to the left and not the WAN port (might be yellow, depends on version number). Computer -> 1st Netgear LAN port and 2nd Netgear LAN port -> TP Link LAN port.

Alternatively, you could use a switch between.

Yes, it could be a setting. For example, the green Ethernet (Energy Efficient) setting you mention in your first post uses lower voltage, which is often fine on short runs, but if that voltage is not high enough for the devices to detect the signals, then you get a poor connection. You have tried the obvious settings ... I'll try to think of another.

The invalid IP error message is likely due to plugging into one device and then plugging into another and back and forth. Doing "ipconfig /release" and then "ipconfig /renew" from a command prompt normally fixes it. Alternatively, you can restart the computer.
 
Jul 20, 2020
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Doing "ipconfig /release" and then "ipconfig /renew" from a command prompt normally fixes it.
I tried to do that, but as soon as I hit the "ipconfig /release", the internet disconnects, requiring the network troubleshooting to fix the "Ethernet doesn't have a valid IP cofiguration" again. I can't do the ipconfig /renew without that.
 
I tried to do that, but as soon as I hit the "ipconfig /release", the internet disconnects, requiring the network troubleshooting to fix the "Ethernet doesn't have a valid IP cofiguration" again. I can't do the ipconfig /renew without that.
Correct ... the release command blanks out your IP address and other information. Ignore the pop-up box and from the same command prompt (cmd in the search box) do ipconfig /renew, which will send a message to your router to request a new IP address, DNS address, gateway, etc (DHCP information)
 
Jul 20, 2020
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Your ISP has "remembered" the MAC address of your first router. You need to contact your ISP, tell them you are switching routers and ask them to clear your line.
Alright, we have a small progress!

So, I contacted the ISP following your advice, and they reset the modem. The cable stopped connecting and disconnecting constantly.
Update: I did a network reset on the computer and the problem returned. This is getting old.
I tried to do an "ipconfig /renew" as per @anotherdrew's request, and now it prints the message: "An error occurred while renewing interface Ethernet: unable to contact your DHCP server. Request has timed out."

I have to ask yet again for additional help, and thank you truly for the help you're getting me so far.
 
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