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I recently installed Ubuntu 13.10 (later upgraded to 14.04 in an unsuccessful attempt to fix the problem) and have been having trouble with the wired Internet. Specifically, the Internet connection is dropping intermittently, maybe for 15-90 seconds every minute or two.

Curiously, I never have any problems pinging another computer plugged into the same switch. Only the external Internet drops. However, I don't have any issues with the external Internet when I plug my MacBook into the same Ethernet switch.

It's not a DNS issue, as the issue persists if I try to ping Google by IP address instead of using google.com.

I actually have two network cards in the machine (each with two Ethernet ports). The cards use different drivers, namely e1000e and ixgbe. I encounter the same problem no matter which card I plug into.

I was originally on Ubuntu 13.10 and kernel 3.11. I upgraded to Ubuntu 14.04 and kernel 3.13.0-20, but it didn't fix the problem. I also tried disabling the 3 interfaces (two ports on the other card and the unused port on the active card) and stopping network-manager, but that didn't seem to have an effect either.

There's nothing obvious in /var/logsyslog or kern.log. In particular, the times when the Internet stops and starts again don't lineup with DHCP renewals.

Any ideas? I'm stumped here, so any help would be very much appreciated.

Thanks!

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3 Answers 3

Is it a clean install of 14.04? Maybe you could try to do that. I've read that upgrading between version is not always 'safe'.

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No, it was an upgrade. I'll try a fresh install, thanks! –  alexrs Apr 1 at 17:57
    
Did it work out? –  user229948 Apr 3 at 20:23

I tried rejigging the network interfaces. I plugged an Ethernet cable into all 4 ports, brought them all up, and re-enabled network-manager. So far, it seems to be working now.

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I am using Ubuntu 14.04 (did a clean install from Ubuntu 13.10 recently) on my Desktop machine. Since an upgrade in 13.10 earlier my system has started showing strange behavior of intermittent disconnections in browsing. At that specific moment pinging proxy halts with more than 80% packet lost. Sometimes its even unreachable as shown below. At that specific moment I get reconnection if I reset LAN connection. By the way LAN connection remains connected always.

Some ping behaviors and ifconfig results are shown below.

user@user-desktop:~$ ping 192.168.0.51 PING 192.168.0.51
(192.168.0.51) 56(84) bytes of data.
64 bytes from 192.168.0.51: icmp_seq=13 ttl=128 time=0.283 ms
64 bytes from 192.168.0.51: icmp_seq=14 ttl=128 time=0.275 ms
64 bytes from 192.168.0.51: icmp_seq=15 ttl=128 time=0.303 ms
64 bytes from 192.168.0.51: icmp_seq=16 ttl=128 time=0.272 ms
64 bytes from 192.168.0.51: icmp_seq=17 ttl=128 time=0.302 ms
64 bytes from 192.168.0.51: icmp_seq=18 ttl=128 time=0.509 ms
64 bytes from 192.168.0.51: icmp_seq=19 ttl=128 time=0.570 ms
64 bytes from 192.168.0.51: icmp_seq=20 ttl=128 time=0.211 ms ^?^C
--- 192.168.0.51 ping statistics ---
40 packets transmitted, 8 received, 80% packet loss, time 39100ms rtt
min/avg/max/mdev = 0.211/0.340/0.570/0.120 ms

user@user-desktop:~$ ping 192.168.0.51 PING 192.168.0.51
(192.168.0.51) 56(84) bytes of data.
From 192.168.1.206 icmp_seq=1 Destination Host Unreachable From
192.168.1.206 icmp_seq=2 Destination Host Unreachable From 192.168.1.206
icmp_seq=3 Destination Host Unreachable From 192.168.1.206 icmp_seq=4
Destination Host Unreachable From 192.168.1.206 icmp_seq=5 Destination
Host Unreachable From 192.168.1.206 icmp_seq=6 Destination Host
Unreachable From 192.168.1.206 icmp_seq=7 Destination Host Unreachable
From 192.168.1.206 icmp_seq=8 Destination Host Unreachable From
192.168.1.206 icmp_seq=9 Destination Host Unreachable From 192.168.1.206
icmp_seq=10 Destination Host Unreachable From 192.168.1.206 icmp_seq=11
Destination Host Unreachable From 192.168.1.206 icmp_seq=12 Destination
Host Unreachable ^C
--- 192.168.0.51 ping statistics ---
13 packets transmitted, 0 received, +12 errors, 100% packet loss, time
12051ms

user@user-desktop:~$ ifconfig
eth0      Link encap:Ethernet  HWaddr 78:ac:c0:bb:67:d4 
          inet addr:192.168.1.206  Bcast:192.168.1.255
Mask:255.255.254.0
          inet6 addr: fe80::7aac:c0ff:febb:67d4/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:240643 errors:0 dropped:0 overruns:0 frame:0
          TX packets:223734 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:25537053 (25.5 MB)  TX bytes:17135945 (17.1 MB)
          Interrupt:19 Memory:f0100000-f0120000

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:478 errors:0 dropped:0 overruns:0 frame:0
          TX packets:478 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:67030 (67.0 KB)  TX bytes:67030 (67.0 KB)
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