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  1. #1
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    Question Ethernet connection not working (sometimes)

    I am running Win8.1/64 Pro. I have a Dell XPS 8700 that has a Realtek PCIe GBE Family Ethernet controller. It also has a Wireless controller, but I have been using only the Ethernet connection. A couple of months ago, Cox installed a new Cisco cable modem and wireless router, and I have been using that wireless connection for most of my devices. However, the PC remained connected to Ethernet. Starting a few weeks ago, the system would boot without any network connection - diagnostics said that an Ethernet cable was not connected. Sometimes I could reboot and the connection recovered; sometimes I had to unplug the PC (to reset everything) and reboot to fix the problem. Over the past couple of days, the Ethernet connection failed consistently and rebooting didn't fix the issue. My cables are good, but I tried swapping Ethernet cables without any success.

    Then, I took my old Netgear N300 (WNR2000V3) wireless router (which I had been using before the latest Cox install) and connected it to my wall Ethernet Plug, and then ran the existing Ethernet wire to the PC. The Ethernet connection then started working. I don't need another wireless access point (the Cox Cisco wireless router is working fine), and the fact that the N300 was seeing and passing the Ethernet signal fine indicated that the wall port and cables were fine. So, I tried swapping out the N300 for a Netgear Prosafe 5 Port 10/100 Ethernet switch. The Ethernet connection then fails again. The pilot lights on the switch shows it is getting a incoming signal and I can see the outgoing connection also working. Looking at the Win8.1 diagnostics gives me a message "Ethernet Doesn't have A Valid IP Configuration". This switch has worked on this PC in the past without any problems. I assumed (incorrectly?) that the Cisco router would assign the proper ID configuration through the switch, as I is just passing the Ethernet signal on to the PC.

    I was going to add "complicated" to my post title, but then it seems to me that networking is always complicated when it doesn't work.

    I can set the Netgear to use the same SSID as the Cisco without any apparent problem, but I don't really need to do that, and I don't see any way to just turn off the wireless connection in the N300 configuration. I have seen some postings here that says the N300 can be used as an additional access point, but I don't understand that configuration, and again, the N300 and the Cisco wireless routers are about 25 feet apart, but the signal doesn't need any boosting - at least from this location.

    Can anyone help me understand what is going here? Windows gets itself involved in this process - when the Ethernet connection dies, it automatically turns on the Wireless connection, so at least the PC boots with Internet connection.

    David

  2. #2
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    Having a good connection from the N300 but not the switch suggest you are not getting a DHCP connection from the Cisco.
    When you have no Ethernet can you run the following and paste it here? This will show us what your connections have in the way of IP addresses and DHCP set up.
    Start > Run, cmd
    ipconfig /all > 0
    Notepad 0

    cheers, Paul

  3. #3
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    Here is what I got when Ethernet was connected via the switch (and not working). (Below this, I have pasted what I got with the N300 connected (via Ethernet). Thanks for your help.

    David

    Via Switch:

    Windows IP Configuration

    Host Name . . . . . . . . . . . . : Win8_64
    Primary Dns Suffix . . . . . . . :
    Node Type . . . . . . . . . . . . : Hybrid
    IP Routing Enabled. . . . . . . . : No
    WINS Proxy Enabled. . . . . . . . : No

    Wireless LAN adapter Local Area Connection* 14:

    Media State . . . . . . . . . . . : Media disconnected
    Connection-specific DNS Suffix . :
    Description . . . . . . . . . . . : Microsoft Wi-Fi Direct Virtual Adapter
    Physical Address. . . . . . . . . : 1A-76-3F-82-A1-A9
    DHCP Enabled. . . . . . . . . . . : Yes
    Autoconfiguration Enabled . . . . : Yes

    Ethernet adapter Bluetooth Network Connection:

    Media State . . . . . . . . . . . : Media disconnected
    Connection-specific DNS Suffix . :
    Description . . . . . . . . . . . : Bluetooth Device (Personal Area Network)
    Physical Address. . . . . . . . . : B8-76-3F-82-A1-AA
    DHCP Enabled. . . . . . . . . . . : Yes
    Autoconfiguration Enabled . . . . : Yes

    Ethernet adapter Ethernet:

    Connection-specific DNS Suffix . :
    Description . . . . . . . . . . . : Realtek PCIe GBE Family Controller
    Physical Address. . . . . . . . . : 90-B1-1C-9E-DF-70
    DHCP Enabled. . . . . . . . . . . : Yes
    Autoconfiguration Enabled . . . . : Yes
    Autoconfiguration IPv4 Address. . : 169.254.51.82(Preferred)
    Subnet Mask . . . . . . . . . . . : 255.255.0.0
    Default Gateway . . . . . . . . . :
    NetBIOS over Tcpip. . . . . . . . : Enabled

    Wireless LAN adapter Wi-Fi:

    Connection-specific DNS Suffix . :
    Description . . . . . . . . . . . : Dell Wireless 1703 802.11b|g|n (2.4GHz)
    Physical Address. . . . . . . . . : B8-76-3F-82-A1-A9
    DHCP Enabled. . . . . . . . . . . : Yes
    Autoconfiguration Enabled . . . . : Yes
    Link-local IPv6 Address . . . . . : fe80::18fd:182f:21dd:ef17%2(Preferred)
    IPv4 Address. . . . . . . . . . . : 192.168.0.24(Preferred)
    Subnet Mask . . . . . . . . . . . : 255.255.255.0
    Lease Obtained. . . . . . . . . . : Saturday, May 2, 2015 10:53:37 AM
    Lease Expires . . . . . . . . . . : Saturday, May 2, 2015 11:53:35 AM
    Default Gateway . . . . . . . . . : 192.168.0.1
    DHCP Server . . . . . . . . . . . : 192.168.0.1
    DHCPv6 IAID . . . . . . . . . . . : 263747135
    DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-19-FF-21-1B-B8-76-3F-82-A1-A9
    DNS Servers . . . . . . . . . . . : 68.105.28.12
    68.105.29.12
    68.105.28.11
    NetBIOS over Tcpip. . . . . . . . : Enabled

    Tunnel adapter isatap.{2DF7EEB4-6CE4-4B58-ABC4-635FA4579388}:

    Media State . . . . . . . . . . . : Media disconnected
    Connection-specific DNS Suffix . :
    Description . . . . . . . . . . . : Microsoft ISATAP Adapter
    Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
    DHCP Enabled. . . . . . . . . . . : No
    Autoconfiguration Enabled . . . . : Yes

    Tunnel adapter Local Area Connection* 13:

    Connection-specific DNS Suffix . :
    Description . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface
    Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
    DHCP Enabled. . . . . . . . . . . : No
    Autoconfiguration Enabled . . . . : Yes
    IPv6 Address. . . . . . . . . . . : 2001:0:5ef5:79fd:28c4:2d5f:bb1f:c7dd(Preferred)
    Link-local IPv6 Address . . . . . : fe80::28c4:2d5f:bb1f:c7dd%8(Preferred)
    Default Gateway . . . . . . . . . : ::
    DHCPv6 IAID . . . . . . . . . . . : 134217728
    DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-19-FF-21-1B-B8-76-3F-82-A1-A9
    NetBIOS over Tcpip. . . . . . . . : Disabled

    Tunnel adapter isatap.{ABB62754-EC9F-4B07-AB84-00468DDA7CDE}:

    Media State . . . . . . . . . . . : Media disconnected
    Connection-specific DNS Suffix . :
    Description . . . . . . . . . . . : Microsoft ISATAP Adapter #2
    Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
    DHCP Enabled. . . . . . . . . . . : No
    Autoconfiguration Enabled . . . . : Yes

    Ethernet connected via the N300 Router:


    Windows IP Configuration

    Host Name . . . . . . . . . . . . : Win8_64
    Primary Dns Suffix . . . . . . . :
    Node Type . . . . . . . . . . . . : Hybrid
    IP Routing Enabled. . . . . . . . : No
    WINS Proxy Enabled. . . . . . . . : No

    Wireless LAN adapter Local Area Connection* 14:

    Media State . . . . . . . . . . . : Media disconnected
    Connection-specific DNS Suffix . :
    Description . . . . . . . . . . . : Microsoft Wi-Fi Direct Virtual Adapter
    Physical Address. . . . . . . . . : 1A-76-3F-82-A1-A9
    DHCP Enabled. . . . . . . . . . . : Yes
    Autoconfiguration Enabled . . . . : Yes

    Ethernet adapter Bluetooth Network Connection:

    Media State . . . . . . . . . . . : Media disconnected
    Connection-specific DNS Suffix . :
    Description . . . . . . . . . . . : Bluetooth Device (Personal Area Network)
    Physical Address. . . . . . . . . : B8-76-3F-82-A1-AA
    DHCP Enabled. . . . . . . . . . . : Yes
    Autoconfiguration Enabled . . . . : Yes

    Ethernet adapter Ethernet:

    Connection-specific DNS Suffix . :
    Description . . . . . . . . . . . : Realtek PCIe GBE Family Controller
    Physical Address. . . . . . . . . : 90-B1-1C-9E-DF-70
    DHCP Enabled. . . . . . . . . . . : Yes
    Autoconfiguration Enabled . . . . : Yes
    IPv4 Address. . . . . . . . . . . : 192.168.1.2(Preferred)
    Subnet Mask . . . . . . . . . . . : 255.255.255.0
    Lease Obtained. . . . . . . . . . : Saturday, May 2, 2015 9:39:52 AM
    Lease Expires . . . . . . . . . . : Sunday, May 3, 2015 9:39:50 AM
    Default Gateway . . . . . . . . . : 192.168.1.1
    DHCP Server . . . . . . . . . . . : 192.168.1.1
    DNS Servers . . . . . . . . . . . : 192.168.1.1
    NetBIOS over Tcpip. . . . . . . . : Enabled

    Wireless LAN adapter Wi-Fi:

    Media State . . . . . . . . . . . : Media disconnected
    Connection-specific DNS Suffix . :
    Description . . . . . . . . . . . : Dell Wireless 1703 802.11b|g|n (2.4GHz)
    Physical Address. . . . . . . . . : B8-76-3F-82-A1-A9
    DHCP Enabled. . . . . . . . . . . : Yes
    Autoconfiguration Enabled . . . . : Yes

    Tunnel adapter isatap.{ABB62754-EC9F-4B07-AB84-00468DDA7CDE}:

    Media State . . . . . . . . . . . : Media disconnected
    Connection-specific DNS Suffix . :
    Description . . . . . . . . . . . : Microsoft ISATAP Adapter
    Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
    DHCP Enabled. . . . . . . . . . . : No
    Autoconfiguration Enabled . . . . : Yes

    Tunnel adapter Local Area Connection* 13:

    Connection-specific DNS Suffix . :
    Description . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface
    Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
    DHCP Enabled. . . . . . . . . . . : No
    Autoconfiguration Enabled . . . . : Yes
    IPv6 Address. . . . . . . . . . . : 2001:0:5ef5:79fd:2ca4:3d48:3f57:fefd(Preferred)
    Link-local IPv6 Address . . . . . : fe80::2ca4:3d48:3f57:fefd%8(Preferred)
    Default Gateway . . . . . . . . . : ::
    DHCPv6 IAID . . . . . . . . . . . : 134217728
    DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-19-FF-21-1B-B8-76-3F-82-A1-A9
    NetBIOS over Tcpip. . . . . . . . : Disabled

  4. #4
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    As it works with the N300, that would rule out your computer as to a registry problem for it dropping the Default Gateway.

    If the Cisco is a separate modem and router, does it still drop out when you wire directly to the modem ?

    If it doesn't then that would point to a defective router and the same if it's a modem/router combo.

    Either way, you should contact the ISP for replacement equipment.

  5. #5
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    The Cisco is a Docis 3 modem with Wi-Fi. One box - it can't be separated. The other issue is that I have to reboot it about once a month because it looses all internet connections. That happened today. I am contacting Cox to see if I can get a replacement. TV, phone, home security have all been very reliable.

    David

  6. #6
    jwoods
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    The obvious question is what was changed right before the issue started...

    You might check what you have done to this point against the steps in this Tom's Hardware article...

    http://www.tomshardware.com/faq/id-2...n-windows.html

    Also note at the bottom of the Tom's page there are three threads marked "solved" for the same issue.
    Last edited by jwoods; 2015-05-03 at 02:21.

  7. #7
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    From the IP config you posted you can see that there is no DHCP server for your Ethernet connection when connected direct, but the wireless is OK. When you connect to the N300 you get an IP config, but the DHCP server is the N300, 192.168.1.1 versus 192.168.0.1.
    The implication is that the Cisco is not providing DHCP via Ethernet for some reason. Can you factory reset the Cisco and see if it behaves, or just wait for a replacement.

    cheers, Paul

  8. #8
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    Paul:

    You are correct - for some reason (about every 30 days) the Cisco Modem/Wi-Fi router stops issuing IP addresses and everything fails. I generally notice this first on my iMac, which is connected via Wi-Fi, and I use that system most. The only solution is to unplug the Cisco Modem/Wi-Fi device, wait 30 seconds, plug it in, and let it reboot. I didn't realize it was also affecting the Ethernet connections too. I have my PC connected now via the Netgear Switch, and it is working fine. The symptom I should have understood was the Windows diagnostic message that no IP address was assigned.

    When you call Cox technical support they tell you to unplug and restart the Cisco device - so this is their standard "fix". I don't know if this is software or hardware, but I suspect hardware. I am going to have to get them out here to replace the Cisco hardware.

    Unfortunately, as I mentioned, this has also apparently disabled my SunPower solar panel connection too - which is connected via Ethernet. I have to research that more. (The SunPower web site now says the disconnect was "resolved", but I still don't see any power production statistics.)

    All my Cox stuff work fine - TV, Phone, Home Security - but the internet needs to be reset every month. My Netgear N300 worked perfectly for three years before the latest Cox "upgrade". Ugh.

    Thanks for the help in tracking this down.

    David

  9. #9
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    One additional note about the Ethernet connection to my Sun Power solar panel system... (This forum thread was mentioned in the current Windows Newsletter, so I guess there is general interest.)

    I called Sun Power and they sent out a technician to check the connection. (Additional note: Sun Power is a great company - I have a 25 year guarantee, and that includes sending the tech for the connection issue - at no cost to me.)

    After checking the connection (the cable was plugged into the Cisco Modem/Router), the tech discovered that one pair on the cable was not working. He replaced the plug on the connection to the Sun Power data logger, and rebooted the logger, and everything is functioning now. What is curious is my 100Mbps system only uses two pair in the cable. _Gigabit_ Ethernet uses all four pairs. My hypothesis at this time is that somehow the router got switched into Gigabit Ethernet mode (for this connection at least), and the existing plug defect caused the connection to fail.

    My house is four years old and is completely wired with 100Mbps cabling and everything (including the Sun Power connection) had been running fine in that mode. Why all four pairs in the Ethernet cable to the Sun Power inverter suddenly became necessary is a mystery.

    Cox confirmed that the Cisco router was running the current version of the Cisco software, but we reloaded the firmware again to make sure nothing had been corrupted. I have to wait a month or so and see if it fails again. If this "no IP address after 30 days" problem continues, I will have Cox replace the Modem/Router (they have said they will do that if I ask).

    Finally, the other discovery yesterday by the Sun Power tech was that the switch that connected all my downstairs Ethernet wall ports had been bypassed (by someone in the past - I can't pin this on Cox for sure, because I have had so may different companies messing with my wiring). My upstairs den - where my PC is connected to Ethernet - was connected directly to the Cox Modem/Router.

    (My house is a Leed Platinum certified home (high energy efficiency) and was constructed as part of an arrangement between Pulte Homes, the DOE, NV Energy, and UNLV. It is _very_ connected. Beyond the Internet, TV, Phone, and Home Security, the solar panels are connected to the internet, my HVAC thermostats are connected to the internet, and my AC compressor is connected to the internet. You should see my wiring closet where all the connections are made! Some of my neighbors have even more - my next door neighbor also has a (huge) battery in his garage that stores and releases electrical power to load shift. The Tesla battery system has been in the news lately, and I would like to hear about it's power efficiency. The NV Energy battery program rebates $350 a year to cover the increased usage because their battery system is so inefficient.)

    David

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