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I just did the upgrade from 17.04 to 17.10, however my wifi Internet no longer works. I,m on a Thinkpad T430. A simple ssh gets "Could not resolve hostname..." Please advise.

Panther - update from comments:

ping 8.8.8.8 works with a round trip of, e.g., 21.6 ms. ping google.com does not

Panther
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147pm
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  • Can you provide more information ? Sounds like an dns problem. How can you post here ? What happens when you ping "google.com" vs "8.8.8.8" ? Is the problem limited to ssh ? – Panther Oct 22 '17 at 03:08
  • your question is vague: unable to resolve hostname could be because you added hostnames to /etc/hosts as a easy way to provide (worked in 1974, why not now) hostnames, to DNS failing, to no connection (password or permissions change), or even access-point down. please provide some info, eg. ifconfig ; route or a ping google.com & ping 8.8.8.8 (google dns) to see if DNS only is down. – guiverc Oct 22 '17 at 03:09
  • ping 8.8.8.8 works with a round trip of, e.g., 21.6 ms. ping google.com does not. ifconfig doesn't turn up anything really different that this machine I'm now using with U17.04. It seems I had this same problem when I upgraded to 17.04. . . . – 147pm Oct 22 '17 at 14:30
  • I did a systemd-resolve --status and got (for wlp3s0) DNS Servers 75.75.75.75 and 75.75.76.76 and DNS Domain hsd1.in.comcast.net. There is no /etc/resolv.conf by the way. Could I create one with nameserver 8.8.8.8, 8.8.4.4? – 147pm Oct 22 '17 at 15:15
  • BTW, doesn't work at Internet cafe, so it's not my home wifi system. Also, a wired connection doesn't work either. – 147pm Oct 22 '17 at 16:26
  • @147pm - In the future, add information to your question by editing rather than the comments. Makes your question easier to understand and people trying to help will make decisions based on your question and may or may not read the comments / go searching for information. – Panther Oct 22 '17 at 16:58

1 Answers1

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It sounds very likely you're dealing with the same DNS issue in this question:

DNS not working after upgrade 17.04 to 17.10

Juho-Miko's answer fixed things for me, I've summarized it here as it might be a little difficult for non-technical users to find/follow his answer:

  1. Confirm the issue is that /etc/resolv.conf is pointing at the wrong spot by running:

    $ systemctl status resolvconf

    You should see the following in the output of the command:

    resolvconf[623]: /etc/resolvconf/update.d/libc: Warning: /etc/resolv.conf is not a symbolic link to /run/resolvconf/resolv.conf

  2. If you do not see the above output, this is NOT your problem. Do NOT proceed to step three.

  3. Run the following commands to fix the issue:

    $ sudo mv /etc/resolv.conf /etc/resolv.conf.old
$ sudo ln -s /run/resolvconf/resolv.conf /etc/resolv.conf
$ systemctl restart resolvconf
Casey
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  • Consider marking such questions as a duplicate or post "possible duplicate of https://askubuntu.com/questions/966870/dns-not-working-after-upgrade-17-04-to-17-10/ " . IMHO, it helps to have one quality answer to such a question rather than 10 or 100 repeat questions on the same problem. You will get different opinions, but I prefer consolidation of effort and community review / updates rather then multiple answers of variable quality. – Panther Oct 22 '17 at 17:02
  • Thanks Casey, this solved it. Yes, call this a duplicate. BTW, why did this happen when I upgraded? – 147pm Oct 22 '17 at 17:21
  • @Panther I'm with you on consolidation, but this is a bit of a weird case. Upgrading the OS is breaking people's internet connection, and there's a decent segment of people who likely won't find the other question because they won't track the issue down to their DNS. My answer is geared toward getting those people up and running. I found this question while trying to figure out how widespread the issue I encountered was. – Casey Oct 22 '17 at 19:05
  • What happens if step 2 fails? /etc/resolv.conf for me is a symbolic link, pointing to /run/resolvconf/resolv.conf, but I still have no connection – user36196 Oct 22 '17 at 21:46
  • I'd try to pin point where things are breaking down and ask a new question with the evidence gathered. The OP had specific DNS issues. – Casey Oct 23 '17 at 02:25