[SOLVED] Laptop server is suddenly unable to connect to the internet

Whooie · 2018-11-03 07:05:25

Hello, I've set one of my old laptops up as a home server for videos and the like and despite it all being fine up until at least Tuesday this week, for some reason the laptop can't connect to the internet via ethernet now. I haven't performed any upgrades or other installations since Tuesday, and I don't think anything has happened to the physical machine (though I suppose that's still a possibility), so I'm kind of at a loss. Here are the results of what I've done to try to diagnose the problem so far:

used my personal laptop to attempt to connect to the internet (via ethernet) using the same cable and router port as the server laptop with total success
tried rebooting the server laptop and reconnecting without success
tried booting from a usb stick with Arch, but couldn't get a connection that way either
tried using the r8168 driver instead of r8169 without success
Here are some relevant terminal outputs:

$ ip addr
...
4: enp3s0: <BROADCAST,MULTICAST> mtu 1500 qdisc fq_codel state DOWN group default qlen 1000
    link/ether 18:67:b0:48:2c:d8 brd ff:ff:ff:ff:ff:ff

$ sudo netctl start wired
Job for netctl@wired.service failed because the control process exited with error code.
See "systemctl status netctl@wired.service" and "journalctl -xe" for details.
$ journalctl -xe
...
-- Unit netctl@wired.service has begun starting up.
Nov 01 15:24:32 rangifer network[633]: Starting network profile 'wired'...
Nov 01 15:24:32 rangifer kernel: r8169 0000:03:00.0 enp3s0: link down
Nov 01 15:24:32 rangifer kernel: IPv6: ADDRCONF(NETDEV_UP): enp3s0: link is not ready
Nov 01 15:24:32 rangifer network[633]: No connection found on interface 'enp3s0' (timeout)
Nov 01 15:24:32 rangifer network[633]: Failed to bring the network up for profile 'wired'
Nov 01 15:24:32 rangifer systemd[1]: netctl@wired.service: Main process exited, code=exited, status=1/FAILURE
Nov 01 15:24:32 rangifer systemd[1]: netctl@wired.service: Failed with result 'exit-code'.
Nov 01 15:24:32 rangifer systemd[1]: Failed to start A basic dhcp ethernet connection.
-- Subject: Unit netctl@wired.service has failed
...

$ cat /etc/netctl/wired
Description='A basic dhcp ethernet connection'
Interface=enp3s0
Connection=ethernet
IP=dhcp
...

$ lspci -v
...
03:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/6411 PCI Express Gigabit Ethernet Controller (rev 06)
Subsystem: Samsung Electronics Co Ltd RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
Flags: bus master, fast devsel, latency 0, IRQ 19
I/O ports at d000 [size=256]
Memory at f7c00000 (64-bit, non-prefetchable) [size=4K]
Memory at f0000000 (64-bit, prefetchable) [size=16K]
Capabilities: <access denied>
Kernel driver in use: r8169
Kernel modules: r8169

$ lsmod | grep r8169
r8169                   90112  0
mii                     16384  1 r8169

$ dmesg | grep r8169
[    9.768735] r8169 Gigabit Ethernet driver 2.3LK-NAPI loaded
[    9.768743] r8169 0000:03:00.0: can't disable ASPM; OS doesn't have ASPM control
[    9.769662] r8169 0000:03:00.0 eth0: RTL8168evl/8111evl, 18:67:b0:48:2c:d8, XID 2c900800, IRQ 31
[    9.769664] r8169 0000:03:00.0 eth0: jumbo features [frames: 9200 bytes, tx checksumming: ko]
[    9.912039] r8169 0000:03:00.0 enp3s0: renamed from eth0
[   13.691525] r8169 0000:03:00.0 enp3s0: link down

$ rfkill list all
0: phy0: Wireless LAN
        Soft blocked: no
        Hard blocked: no
1: hci0: Bluetooth
        Soft blocked: no
        Hard blocked: no

$ sudo ip link set enp3s0 up
$ sudo dhcpcd -d enp3s0
dhcpcd-7.0.8 starting
enp3s0: executing `/usr/lib/dhcpcd/dhcpcd-run-hooks' PREINIT
enp3s0: executing `/usr/lib/dhcpcd/dhcpcd-run-hooks' NOCARRIER
enp3s0: waiting for carrier
timed out
dhcpcd exited

Any thoughts? Comparing the dmesg output with that of me personal laptop, it seems like the problem could be there, but I'm really starting to feel like I don't have the technical knowledge to properly interpret this information. Should I try buying a usb ethernet adapter? I think the weirdest thing is that it seems like whatever caused the disconnection was spontaneous.

Last edited by Whooie (2018-11-17 02:30:23)

ewaller · 2018-11-03 14:50:23

What are the output of:
ip link
uname -a
and
pacman -Q linux (Assuming you are using the stock kernel.)

Why did you include the results of rfkill; this is a wired connection. Or did I miss something?
It truly sounds like there is no carrier; despite the cable working with another machine. Does the link light on the NIC come on when the cable is attached? How about the link light on the router?

Whooie · 2018-11-03 17:51:32

$ ip link
1: lo: <LOOPBACK,IP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: enp3s0: <BROADCAST,MULTICAST> mtu 1500 qdisc fq_codel state DOWN mode DEFAULT group default qlen 1000
    link/ether 18:67:b0:48:2c:d8 brd ff:ff:ff:ff:ff:ff
3: wlp2s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether b4:b6:76:81:01:af brd ff:ff:ff:ff:ff:ff

$ uname -a
Linux rangifer 4.18.16-arch1-1-ARCH #1 SMP PREEMPT Sat Oct 20 22:06:45 UTC 2018 x86_64 GNU/Linux

$ pacman -Q linux
linux 4.18.16.arch1-1

I posted in the /r/archlinux subreddit before this and someone there suggested rfkill it as a weird shot in the dark; this is definitely a wired connection.
Ok so I'm still pretty new to this sort of thing in general and maybe my understanding is a bit fuzzy, what exactly is a carrier? Is it not the router or otherwise the service which provides internet connections? There's no light on the machine, but the light on the router blinks slowly, maybe once every 3 or 4 seconds.

Last edited by Whooie (2018-11-03 18:17:08)

ewaller · 2018-11-03 20:13:45

And when the other computer is connected to the cable the router link light is solid? Or does it blink?

Unlike asynchronous serial ports (RS-232) which allow the line to go idle, Ethernet ports are always sending data in both directions and generally starts when two ports are connected to each other If there is nothing to send, idle packets are sent. (Mostly. There are inter record gaps that are required). This activity can be detected at both ends to know whether it is possible to communicate or not. When a carrier is present, a device will light its link light. Most 100Base-T links are full duplex using one twisted pair for Tx, and one for Rx. 1000Base-T is a bit more complex using multiple pairs and (I think) half duplex.

The point being, a carrier is a prerequisite for communication and, unlike an RF system, a carrier means that packets are being received -- but they may be idle packets.

What speed are you expecting? Are you expecting half duplex or full duplex? The computer that works -- at what rate is it connecting? Is that rate supported by the system that does not work?
Have you tried a different cable?
Can you connect the computer that does not work to the one that does? do they both have link lights? can you establish a point to point connection between the two?

Whooie · 2018-11-03 22:26:12

When I connect the other computer to the router, the light is solid on both ends (this one happens to have a light on its end).

Speeds should be around 70 Mb/s down and 5-6 Mb/s up, and I'm not really sure what half/full duplex indicates, but dmesg | grep e1000e (e1000e is the working computer's driver) prints out lines with Link is Up 1000 Mbps Full Duplex, so I guess full?

I have tried different cables and router ports, and while I'm not sure how to actually establish an ethernet connection between the two computers, I did try physically connecting the them with the same cord, and got the same slow blink on the computer than works as on the router.

If there were a physical problem with the computer than doesn't work, say with its connector, would the kernel module be able to detect it (as in, can we rule out a hardware problem)? Would this isuue get solved if I use a different interface, like a usb ethernet adapter?

EDIT: Looks like it was a hardware problem. I got a usb-ethernet adapter and it all works.

Last edited by Whooie (2018-11-17 02:31:05)

Arch Linux

#1 2018-11-03 07:05:25

[SOLVED] Laptop server is suddenly unable to connect to the internet

#2 2018-11-03 14:50:23

Re: [SOLVED] Laptop server is suddenly unable to connect to the internet

#3 2018-11-03 17:51:32

Re: [SOLVED] Laptop server is suddenly unable to connect to the internet

#4 2018-11-03 20:13:45

Re: [SOLVED] Laptop server is suddenly unable to connect to the internet

#5 2018-11-03 22:26:12

Re: [SOLVED] Laptop server is suddenly unable to connect to the internet

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