Ethernet link not detected in ubuntu 14.04 after update

Question

Since I ran some update in the past week or so, I have not been able to get a wired connection. Specifically:

• Initially, during boot up, the ethernet link light is on As ubuntu boots up, the link light will go off Ubuntu reports cable is disconnected If I boot into Windows 7, I can use the internet without issue.

My problem is similar to what is described at: Ethernet Lights Not On When Cable Connected And Not Working

lspci entry:

Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 06)

sudo ethtool eth0:

Settings for eth0:
    Supported ports: [ TP MII ]
    Supported link modes:   10baseT/Half 10baseT/Full 
                            100baseT/Half 100baseT/Full 
                            1000baseT/Half 1000baseT/Full 
    Supported pause frame use: No
    Supports auto-negotiation: Yes
    Advertised link modes:  10baseT/Half 10baseT/Full 
                            100baseT/Half 100baseT/Full 
                            1000baseT/Half 1000baseT/Full 
    Advertised pause frame use: Symmetric Receive-only
    Advertised auto-negotiation: Yes
    Speed: 10Mb/s
    Duplex: Half
    Port: MII
    PHYAD: 0
    Transceiver: internal
    Auto-negotiation: on
    Supports Wake-on: pumbg
    Wake-on: g
    Current message level: 0x00000033 (51)
                   drv probe ifdown ifup
    Link detected: no

ifconfig -a

eth0      Link encap:Ethernet  HWaddr d4:3d:7e:26:b2:20
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:300 errors:0 dropped:0 overruns:0 frame:0
          TX packets:300 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:25463 (25.4 KB)  TX bytes:25463 (25.4 KB)

lxcbr0    Link encap:Ethernet  HWaddr 7a:01:dd:5c:17:99  
          inet addr:10.0.3.1  Bcast:10.0.3.255  Mask:255.255.255.0
          inet6 addr: fe80::7801:ddff:fe5c:1799/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:77 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:0 (0.0 B)  TX bytes:11788 (11.7 KB)

syslog:

Feb  8 18:20:42 newdesk kernel: [    4.048721] r8169 0000:03:00.0 eth0: link down
Feb  8 18:20:42 newdesk kernel: [    4.048751] r8169 0000:03:00.0 eth0: link down
Feb  8 18:20:42 newdesk kernel: [    4.048760] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
Feb  8 18:20:42 newdesk kernel: [    4.048905] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready

As I lack another network card, I can only use windows right now. Advice on how to fix this is appreciated.

Thanks!

Answer 1

I can confirm this bug. Faced same issue and It's not wiring problem, it's problem of r8169 driver that appeared recent update. I think they have already found a bug in this module https://lkml.org/lkml/2015/2/21/161

A temporary fix could be building original realtek driver (r8168) and replace current r8169 with it.

https://unixblogger.wordpress.com/2011/10/18/the-pain-of-an-realtek-rtl8111rtl8168-ethernet-card/

1. install requirements

   sudo apt-get install build-essential

2. get and extract the latest driver from Realtek website, enter the directory you unpacked driver to

3. build & install driver:

   sudo make clean modules

   sudo make install

4. make sure r8168.ko is present in your kernel drivers:

   sudo locate -i r8168

   one of lines in the output should be something like this:

   /modules/3.13.0-46-generic/kernel/drivers/net/ethernet/realtek/r8168.ko

5. ban r8169 and rebuild kernel depencies

   sudo echo “blacklist r8169″ >> /etc/modprobe.d/blacklist.conf

   sudo depmod -a

6. Make it available for boot

   sudo echo “r8168″ >> /etc/modules

7. After reboot check the loaded driver

   lspci -v|grep -A 7 Realtek

   Last line should be "Kernel driver in use: r8168″

I hope this helps.