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Recently I've switched fully to Ubuntu after having a huge fuss with Windows. Even though I'd used Ubuntu before, my knowledge about Ubuntu and Linux in general is still very much to be desired. So please excuse any dumb mistakes or questions. Previously I had used Ubuntu 17.10, and when I updated to 18.04, I began to have trouble with my internet connection. It's wired Ethernet, and I've followed a ton of other tutorials and am still having trouble. Here is some info that should pertain to the topic at hand, and if there is anything else you need just ask and I'll update the post.

lspci

00:00.0 Host bridge: Intel Corporation Xeon E3-1200 v6/7th Gen Core Processor Host Bridge/DRAM Registers (rev 06)

00:01.0 PCI bridge: Intel Corporation Skylake PCIe Controller (x16) (rev 06)

00:08.0 System peripheral: Intel Corporation Skylake Gaussian Mixture Model

00:14.0 USB controller: Intel Corporation 200 Series PCH USB 3.0 xHCI Controller

00:14.2 Signal processing controller: Intel Corporation 200 Series PCH Thermal Subsystem

00:16.0 Communication controller: Intel Corporation 200 Series PCH CSME HECI #1

00:17.0 SATA controller: Intel Corporation 200 Series PCH SATA controller [AHCI mode]

00:1c.0 PCI bridge: Intel Corporation 200 Series PCH PCI Express Root Port #7 (rev f0)

00:1f.0 ISA bridge: Intel Corporation 200 Series PCH LPC Controller (B250)

00:1f.2 Memory controller: Intel Corporation 200 Series PCH PMC

00:1f.3 Audio device: Intel Corporation 200 Series PCH HD Audio

00:1f.4 SMBus: Intel Corporation 200 Series PCH SMBus Controller

01:00.0 VGA compatible controller: NVIDIA Corporation GP108 (rev a1)

01:00.1 Audio device: NVIDIA Corporation GP108 High Definition Audio Controller (rev a1)

02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 15)





ifconfig -a

enp2s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 4096

        inet 129.93.213.104  netmask 255.255.255.0  broadcast 129.93.213.255

        ether 30:9c:23:3f:a4:e1  txqueuelen 1000  (Ethernet)

        RX packets 29736  bytes 21675467 (21.6 MB)

        RX errors 0  dropped 0  overruns 0  frame 0

        TX packets 14893  bytes 2650128 (2.6 MB)

        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

        device interrupt 121  base 0x5000  



lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536

        inet 127.0.0.1  netmask 255.0.0.0

        inet6 ::1  prefixlen 128  scopeid 0x10<host>

        loop  txqueuelen 1000  (Local Loopback)

        RX packets 6366  bytes 711610 (711.6 KB)

        RX errors 0  dropped 0  overruns 0  frame 0

        TX packets 6366  bytes 711610 (711.6 KB)

        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0





sudo lshw -C network

  *-network                 

       description: Ethernet interface

       product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller

       vendor: Realtek Semiconductor Co., Ltd.

       physical id: 0

       bus info: pci@0000:02:00.0

       logical name: enp2s0

       version: 15

       serial: 30:9c:23:3f:a4:e1

       size: 1Gbit/s

       capacity: 1Gbit/s

       width: 64 bits

       clock: 33MHz

       capabilities: pm msi pciexpress msix bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation

       configuration: autonegotiation=on broadcast=yes driver=r8168 driverversion=8.045.08-NAPI duplex=full ip=129.93.213.104 latency=0 link=yes multicast=yes port=twisted pair speed=1Gbit/s

       resources: irq:121 ioport:d000(size=256) memory:df104000-df104fff memory:df100000-df103fff

It's very possible the issue resides outside of your Ubuntu machine. I've had this issue in the past and it ended up being a faulty port on my switch. Here's a few things you can try on that tangent:

1. Replace the Ethernet cable/make sure it's the correct cable for gigabit (Cat5e, Cat6).


2. Check other devices on your network for similar issues. If they are experiencing the same problem, it's likely the fault of either a switch or your router, depending on how your network is laid out.


3. Look at the output of ifconfig -a after the computer has been running for a couple hours. Check for any of the error categories: dropped, overruns, collisions, etc. These typically won't show up immediately after boot unless the problem is really prominent. Each of these categories indicates something going wrong (except collisions if your computer is connected to a hub) with a different aspect of your computer's connection.


4. Plug your Ubuntu machine into another port on your switch/router. Try to duplicate the problem.

@Epicranger, I have the same network hardware and the same problem started a few days ago running 16.04 LTS.

Have also cranked through a process of elimination, the most telling being that the problem is not seen in Win 7. Since I would rather be tortured than run Windows (which actually IS tortnure), finding a solution is not optional.

So posting this as a placeholder for now, returning w/ fix shortly...