SOLVED Strange internet connectivity issue

[LK51]

Today a Windows 10 update screwed my Grub2 bootloader on my dual boot desktop. Used “Boot Repair” to fix the issue. All went well to facilitate Grub booting into either LM18.3 and/or Win10. I use LM about 95% of the time, and once things were up and running again I could not connect to internet via Chrome or Firefox in LM. Also update manager was crippled in not being able to get out to the internet. I believe the issue may be OS related because...

- Network Connection applet inidcates an active connection
- The same machine has full internet connectivity under Win10
- Gufw Firewall has been turned off
- I can reach both modem and router interfaces without problems via web browser
- There had been no network connectivity issue previously (i.e., this system configuration has been running flawlessly for several months)

While I am a fairly experienced LM user, I don’t have enough expertise to know how to troubleshoot this issue. Would appreciate any guidance/advice on how to proceed. I’m happy to post any system data that is relevant, just let me know. Thanks...

[acerimusdux]

Maybe a dns issue. Maybe try changing the router DNS to something else (like google 8.8.8.8 ) Can you ping outside adresses?

[LK51]

Thanks acerimusdux ,
ping of 203.0.178.191 was successful
ping of 127.0.0.1 was too
ping of iinet.net.au was not

So, as you suggested, this indicates a DNS problem right? Any suggestion on how to address this?

[trytip]

when this happens restart your router

[LK51]

No change, issue persists.

[acerimusdux]

Have you tried changing the DNS server on the router? Maybe the one being provided by your ISP isn't working properly. Some public ones you can try:

Google: 8.8.8.8 and 8.8.4.4
OpenDNS: 208.67.220.220 and 208.67.222.222

You could also try:

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systemd-resolve google.com

to verify that DNS isn't working on your machine. And then try:

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systemctl reload-or-restart resolvconf

to restart it.

[LK51]

Thanks for the suggestion, and for hanging in there with me on this. The response to the resolve command is...
$ systemd-resolve google.com
google.com: resolve call failed: All attempts to contact name servers or networks failed

And the restart command has no effect on this.

My "logic" is that this is not a router or modem based issue in that those appliances resolve domain names for the Win10 OS on this same machine (dual booted to a single partioned SSD). Also the laptop I am using to reach the forum now is connected via wifi and running a dual boot with LM18.3 and Win10 as well with no issues. So does this make sense that the issue is somehow located in the desktop's LM18.3 installation as opposed to router or modem?

[LK51]

Tried adding suggested DNS servers to network connection profile, but didn't correct issue. (See attached screenshot)

Also booted from a LM18.3 flash drive. Was able to call up web pages normally from the live environment.

I'm thinking that since not only web browsers are having this issue, but that also web services like update manager are having it too, that there is some DNS setting(s) in configuration files that needs to be corrected. Are there system files that manage this function?

[trytip]

i had issues connecting to internet after rebooting from windows 8. dns flush your linux, hard unplug any wifi or wired, restart router usually does the trick

the correct format is this (use whatever dns you want, the dns in my snap is for tutorial use only, I don't use this one. i use dnswatch it's slow as molasses many times, but it's not logging traffic) do not require the checkmark for ipv4 addressing after changing dns needs a flush. rightclick the nettray icon disable/enable the connection to kickstart the new one or unplugh the cable from your computer

[acerimusdux]

Well you shouldn't need to put anything there in the connection info for the nameserver (DNS server), that should be blank, it should be getting that from the router if dhcp is working. Try this:

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cat /var/log/syslog|grep "NetworkManager\|dhclient"

I can't figure why there appears to be no resolver when you've already restarted it, so either it's failing to start or something else is failing. Either way, there should be an error message somewhere. The logs should show the network manager activating the interface, then declaring the state as "CONNECTING", then network manager calling dhclient, dhclient making a dhcp request to the router, network manager assigning the IP address, gateway, and nameserver, then network manager changing the state to "CONNECTED", and then finally setting your local network as default for routing and DNS.

It looks like somewhere along the line dhcp isn't succeeding in setting up your DNS

Also try dmesg -l err.

And one more, to see what things are really running and active:

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systemctl --all list-units {*netw*,*resolv*}

[LK51]

cat /var/log/syslog|grep "NetworkManager\|dhclient"cat /var/l returns

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Jun  6 14:31:29 OptiPlex-7010 NetworkManager[845]: <info>  [1528309889.3564] device (eno1): state change: activated -> deactivating (reason 'user-requested') [100 110 39]
Jun  6 14:31:29 OptiPlex-7010 NetworkManager[845]: <info>  [1528309889.3567] manager: NetworkManager state is now DISCONNECTING
Jun  6 14:31:29 OptiPlex-7010 NetworkManager[845]: <info>  [1528309889.3592] audit: op="device-disconnect" interface="eno1" ifindex=2 pid=1584 uid=1000 result="success"
Jun  6 14:31:29 OptiPlex-7010 NetworkManager[845]: <info>  [1528309889.3600] device (eno1): state change: deactivating -> disconnected (reason 'user-requested') [110 30 39]
Jun  6 14:31:29 OptiPlex-7010 NetworkManager[845]: <info>  [1528309889.3929] dhcp4 (eno1): canceled DHCP transaction, DHCP client pid 2194
Jun  6 14:31:29 OptiPlex-7010 NetworkManager[845]: <info>  [1528309889.3929] dhcp4 (eno1): state changed bound -> done
Jun  6 14:31:29 OptiPlex-7010 NetworkManager[845]: <info>  [1528309889.3939] dns-mgr: Writing DNS information to /sbin/resolvconf
Jun  6 14:31:29 OptiPlex-7010 NetworkManager[845]: /etc/resolvconf/update.d/libc: Warning: /etc/resolv.conf is not a symbolic link to /run/resolvconf/resolv.conf
Jun  6 14:31:29 OptiPlex-7010 NetworkManager[845]: <info>  [1528309889.4208] manager: NetworkManager state is now DISCONNECTED
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1327] device (eno1): Activation: starting connection 'Wired connection 1' (2b4b82a9-7c47-3b82-8ca0-911cba953629)
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1329] audit: op="connection-activate" uuid="2b4b82a9-7c47-3b82-8ca0-911cba953629" name="Wired connection 1" pid=1584 uid=1000 result="success"
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1330] device (eno1): state change: disconnected -> prepare (reason 'none') [30 40 0]
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1332] manager: NetworkManager state is now CONNECTING
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1339] device (eno1): state change: prepare -> config (reason 'none') [40 50 0]
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1347] device (eno1): state change: config -> ip-config (reason 'none') [50 70 0]
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1353] dhcp4 (eno1): activation: beginning transaction (timeout in 45 seconds)
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1370] dhcp4 (eno1): dhclient started with pid 2487
Jun  6 14:31:34 OptiPlex-7010 dhclient[2487]: DHCPREQUEST of 192.168.1.139 on eno1 to 255.255.255.255 port 67 (xid=0xd7cddea)
Jun  6 14:31:34 OptiPlex-7010 dhclient[2487]: DHCPACK of 192.168.1.139 from 192.168.1.1
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1723]   address 192.168.1.139
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1723]   plen 24 (255.255.255.0)
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1723]   gateway 192.168.1.1
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1724]   server identifier 192.168.1.1
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1724]   lease time 86400
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1724]   nameserver '192.168.254.254'
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1724]   nameserver '207.91.5.20'
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1724]   nameserver '192.168.1.1'
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1724]   domain name 'Home'
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1724] dhcp4 (eno1): state changed unknown -> bound
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1739] device (eno1): state change: ip-config -> ip-check (reason 'none') [70 80 0]
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1743] device (eno1): state change: ip-check -> secondaries (reason 'none') [80 90 0]
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1746] device (eno1): state change: secondaries -> activated (reason 'none') [90 100 0]
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1747] manager: NetworkManager state is now CONNECTED_LOCAL
Jun  6 14:31:34 OptiPlex-7010 dhclient[2487]: bound to 192.168.1.139 -- renewal in 39394 seconds.
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1768] manager: NetworkManager state is now CONNECTED_GLOBAL
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1769] policy: set 'Wired connection 1' (eno1) as default for IPv4 routing and DNS
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1770] dns-mgr: Writing DNS information to /sbin/resolvconf
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: /etc/resolvconf/update.d/libc: Warning: /etc/resolv.conf is not a symbolic link to /run/resolvconf/resolv.conf
Jun  6 14:31:34 OptiPlex-7010 NetworkManager[845]: <info>  [1528309894.1921] device (eno1): Activation: successful, device activated.
Jun  6 14:31:35 OptiPlex-7010 NetworkManager[845]: <info>  [1528309895.8816] dhcp6 (eno1): activation: beginning transaction (timeout in 45 seconds)
Jun  6 14:31:35 OptiPlex-7010 NetworkManager[845]: <info>  [1528309895.8834] dhcp6 (eno1): dhclient started with pid 2549
Jun  6 14:31:36 OptiPlex-7010 dhclient[2549]: XMT: Info-Request on eno1, interval 960ms.
Jun  6 14:31:37 OptiPlex-7010 dhclient[2549]: XMT: Info-Request on eno1, interval 1840ms.
Jun  6 14:31:38 OptiPlex-7010 dhclient[2549]: XMT: Info-Request on eno1, interval 3580ms.
Jun  6 14:31:42 OptiPlex-7010 dhclient[2549]: XMT: Info-Request on eno1, interval 7090ms.
Jun  6 14:31:49 OptiPlex-7010 dhclient[2549]: XMT: Info-Request on eno1, interval 14070ms.
Jun  6 14:32:03 OptiPlex-7010 dhclient[2549]: XMT: Info-Request on eno1, interval 27530ms.
Jun  6 14:32:21 OptiPlex-7010 NetworkManager[845]: <warn>  [1528309941.6243] dhcp6 (eno1): request timed out
Jun  6 14:32:21 OptiPlex-7010 NetworkManager[845]: <info>  [1528309941.6244] dhcp6 (eno1): state changed unknown -> timeout
Jun  6 14:32:21 OptiPlex-7010 NetworkManager[845]: <info>  [1528309941.6251] dhcp6 (eno1): canceled DHCP transaction, DHCP client pid 2549
Jun  6 14:32:21 OptiPlex-7010 NetworkManager[845]: <info>  [1528309941.6251] dhcp6 (eno1): state changed timeout -> done

I noted the line "Warning: /etc/resolv.conf is not a symbolic link to /run/resolvconf/resolv.conf"

dmesg -l err returns no list/output

systemctl --all list-units {*netw*,*resolv*} returns

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  UNIT                                       LOAD      ACTIVE   SUB    DESCRIPTION
● org.freedesktop.network1.busname           not-found inactive dead   org.freedesktop.network1.busname
  systemd-networkd-resolvconf-update.path    loaded    inactive dead   Trigger resolvconf update for networkd DNS
  networking.service                         loaded    active   exited Raise network interfaces
  resolvconf.service                         loaded    active   exited Nameserver information manager
  systemd-networkd-resolvconf-update.service loaded    inactive dead   Update resolvconf for networkd DNS
  systemd-networkd.service                   loaded    inactive dead   Network Service
  network-online.target                      loaded    inactive dead   Network is Online
  network-pre.target                         loaded    active   active Network (Pre)
  network.target                             loaded    active   active Network

LOAD   = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB    = The low-level unit activation state, values depend on unit type.

9 loaded units listed.
To show all installed unit files use 'systemctl list-unit-files'.

Noted the "inactive/dead" status where listed.
Not sure what this mean or how to correct.

[acerimusdux]

Try this:

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apt install --reinstall resolvconf

That should work. If it doesn't, you can try to restore the missing symlink directly:

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sudo ln -nsf ../run/resolvconf/resolv.conf /etc/resolv.conf

[LK51]

Thanks, will try and let you know the outcome.

[LK51]

acerimusdux

This corrected the problem
...you can try to restore the missing simlink directly:
sudo ln -nsf ../run/resolvconf/resolv.conf /etc/resolv.conf

I'm posting this reply from the affected computer. Web browsing and Update Manager are now working without issue. Thanks for your help and patience to get this problem identified and corrected.