Question Troubleshooting an Ethernet issue ?

[RcknRich]

Hello,

I recently purchased an Arris SB8200 cable modem to replace my broken Linksys I have had for years. I have an old Cisco Linksys E2500 router. I contacted my Xfinity provider to connect my new Arris modem. I have wifi but no ethernet connection. When I run Windows diagnostics it says:

" An Ethernet cable is not properly plugged in or might be broken "

My question is could the router have suddenly gone bad? All the lights are green and were working fine with my prior modem. Now I installed a new modem and no longer have ethernet. I double checked the cables and again all the lights show green, Feeling frustrated like I am missing something stupid.

 

[kanewolf]

Hello,
I hope this is the right area to ask this question. I recently purchased an Arris SB8200 cable modem to replace my broken Linksys I have had for years. I have an old Cisco Linksys E2500 router. I contacted my Xfinity provider to connect my new Arris modem. I have wifi but no ethernet connection. When I run a windows diagnostics it says, An Ethernet cable is properly not plugged in or might be broken.
My question is could the router have suddenly gone bad? All the lights are green and were working fine with my prior modem. Now I installed a new modem and no longer have ethernet. I double checked the cables and again all the lights show green, Feeling frustrated like I am missing something stupid.

Unlikely. First guess is that you have the link speed set to 1GE rather than autonegotite.

 

[BFG-9000]

Unlikely. First guess is that you have the link speed set to 1GE rather than autonegotite.

Which would be a problem as E2500 has no gigabit ports. 10/100 only.

 

[RcknRich]

Okay. Sorry for the delay. Thank you for the replies. Update. I called Xfinity to tell them I had no internet, Come to find out when they activated the new modem, they forgot to transfer my account from the old modem over to the new. Basically claiming I did not have internet service with them which was a joke. Okay they fixed it. However I am still having issues establishing ethernet, I connected a cable from the routerto the laptap to access the ip address under admin to create the username/password for the modem. But when I connect the cable it will not work.(Cable is fine nothing wrong with it). Again this is an old router as stated in the previous message. Could this be the issue as to why it will not allow me access to connect on the laptop? Is itime to change out the router? I know it's old and outdated.

 

[bill001g]

What does IPCONFIG /all say about the ethernet port. Is it disconnected state, which indicates a hardware issue or is the port up but does not have valid IP addresses.

If you do not get a IP address but the port is up then there are couple things. What I would do first is factory reset the router so you know that no old configuration is blocking stuff. If for example you put the router into bridge mode at some time in the past it will not give out DHCP ip addresses.

If this still doesn't work you could I guess try to manually set IP/mask/gateway in the correct range for your router. This assumes the router is actually functioning and has some strange DHCP issue.

 

[RcknRich]

I don't know to attach a photo so I typed it all out.
--------------------------------------------------------------
Ethernet adapter Ethernet:
Media State:Media Disconnected
Connection -specific DNS suffix. : hsd1.ca.comcast.net


Wireless Lan Adapter Wi-Fi:

Connection-specific DNS suffix . :
IPv6 Address. . . . . . . . . . . : 2601:642:4c02:56de:ddc1:f62f:43d3:367b80
Temporary IPv6 address:2601:642:4c02:56de:8d3:a81c:ab13:53cb
Link -local IPv6 address:fe80:a286:3ef9:82d2:45dc%16
IPv4 address:172.20.20.20
Subnet Mask:255.255.255.0
Default Gateway:fe80::ff:fe02::202%16
172.20.20.1

Ethernet adapter Bluetooh Network Connection:

Media State: Media disconnected
Connection -specific DNS suffix

 

[bill001g]

That was a lot of effort.

There is a sticky someplace on one of the main forums that tell how to post photos/screen caps.

So first it seems you have some other router that you are connecting to via wifi. It is using a very uncommon ipblock. It is perfectly valid private IP block it is just not commonly used by home users. I don't think it is your linksys but maybe?

This is not causing the ethernet issue. You can actually have both the ethernet and wifi connected to the same router or even different routers. Not really recommended unless you really know what you are doing.

When it is in a disconnected state it generally means there is some kind of hardware issue.

Do you have any other equipment you can test with. Key is to determine if it is the pc the router or maybe the cable.

What you could do is plug the pc directly into the modem to test. You likely would have to reboot the modem. The modem locks onto the first mac address it sees and if you change what you plug in you have to reboot it. Your pc should actually get a public IP address. You at least want to verify that the port does not still say disconnected.

This is not something you want to leave connected any longer than you need to for testing.

If this also does not work then I am not so sure. It is most times bad cables but the only other option tends to be a bad port on the pc which you can't really fix. This is very basic electical thing at the hardware level so it is not likely a device driver.

If this works then it become a bit more problematic. Do the lights on the router change when you plug cables in. The router maybe in some strange state. Factory reset tends to be the only option. If the router lost the firmware it becomes a challenge. Most new routers have a way to recover them, it is still rather tedious. Its been so long I forget about linksys. Cisco sold them many years ago. The best search is for your router and the term "bricked" or "brick". Many times you find instructions on how to recover router because people attempt to load third party firmware and mess it up. Some get rather crazy like soldering a serial connection to the router motherboard.

Then again you can find many routers for under $50 that will be massively better than yours. I think the new name for the technology it uses is wifi4 but better called 802.11n

 

[dingo07]

Like @bill001g stated already, if you connect the laptop via ethernet cable directly to the modem, and reboot the modem, and you don't have internet then your NIC in the laptop is the issue.

Whether it's broken or not will need more testing - like are the ethernet settings for the Ethernet Adapter set correctly? DHCP enabled when you go into settings for IPv4?

If all the setting are correct for the Ethernett Adapter, then it's possible the drivers for the NIC are the culprit. Try updating them.

If the drivers are all correct then the port has failed and the only fix is a new mainboard for the laptop.

I would log into the router and Factory Reset it. If all else fails and you want to replace it, get yourself the new Ubiquiti Cloud Gateway Fiber.

 

[cruisetung]

run "tracert 8.8.8.8" command and post result