Hi LQ:

I have been running Ubuntu 18.04/20.04 for just over a year without any noticeable problems. I work in a busy environment that hasn't allowed me time to learn anything more than the most basic aspects of Ubuntu, and I have just found an issue that requires help to resolve.

My problem:
Wifi works fine from my home, but when I try to connect to a different network, either private or public, the wifi area of the notification bar says it is connected but I can't connect to any sites. I get a variety of error messages in the browser. The most frequent message is that the host connection cannot be resolved.

What I've tried:
1. A coworker who uses Ubuntu suggested upgrading from 18.04 to 20.04. I did this, but the problem was not resolved.
2. The same coworker suggested that I test my wifi by creating a bootable USB via Unetbootin. I did this, booted into a clean install of Ubuntu 20.04, and found that the problem is resolved. While this shows that my current installation has problems, my work environment can't be interrupted to rebuild my OS.

I need to find a way to resolve this networking issue without the need to perform a full replacement of the OS.

Thanks for the help!

JP

The first thing to do is try from the command line to ping to something on the internet. Something like "ping -c 4 8.8.8.8" should give you 4 return packets.
Try it again with "ping -c 4 google.com"

If the first one works then you are most definitely connected.
If the second works then there is no problem, but if it fails then the issue is likely in how your system is resolving dns.

The fact that it works when booted to the live image already points to resolving host names, but the ping will confirm that.

What is in /etc/resolv.conf? Post the output of "cat /etc/resolv.conf"

What do you see if you run "dig google.com"? Post the output.

1 members found this post helpful.

Thanks for the quick reply, Computersavvy!
I'll test your suggestions as soon as I can and post the requested results.
FYI: My access to networks other than my working one will be less frequent in the coming week, so it may be a few days before I post again.
JP

I've run the Ping and Dig commands. Output shown below:

:~$ ping -c 4 8.8.8.8
PINT 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=114 time=658 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=114 time=614 ms
64 bytes from 8.8.8.8: icmp_seq=3 ttl=114 time=613 ms
64 bytes from 8.8.8.8: icmp_seq=4 ttl=114 time=611 ms

--- 8.8.8.8 print statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3005ms
rtt min/avg/max/mdev = 611.017/623.919/657.635/19.501 ms

:~ping -c 4 google.com
ping: google.com: Name or service not known


I tried running "cat /etc/resolv.conf", but got the message:
cat: /etc/resolv.conf: No such file or directory


:~$ dig google.com
; <<>> DiG 9.16.1-Ubuntu <<>> google.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER>>- opcode: QUERY, status: SERVFAIL, id: 13458
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;;OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
; COOKIE: e7a0768532a84fc301000000613f4310c1c7982f598a1684 (good)
;; QUESTION SECTION:
;google.com. IN A

;; Query time: 76 msec
;; SERVER: ::1#53(::1).
;; WHEN: Mon Sep 13 08:24:48 EDT 2021
;; MSG SIZE rcvd: 67


I also tried connection to a different wifi, one that requires login. The browser tried to open a login page, by instead showed:

"Hmm. We're having trouble finding that site.
We can't connect to the server at n38.network-auth.com."


Thanks for the help,
JPru

So that can definitely be an issue. For 20.04, by default the file should be a link to the systemd file, try running this and restarting:

In my 9/13 post, the CAT command reported the resolv.conf file as not existing, however when I tried creating the link via the LN command, I got this response:

ln: Failed to create symbolic link '/etc/resolv.conf': File exists

Try doing an "ls -l /etc/resolv.conf" to confirm it does exist and verify it is functional link. What you should see is something like
If the /etc/resolve.conf part of that line is green then it is working as it should. If it is red then the link is broken.

If broken then you will need to find out why the file /run/systemd/resolve/stub-resolv.conf is not present/readable.

Please post the output of both the ls command above and "cat /run/systemd/resolve/stub-resolv.conf"

The results of ls -l /etc/resolv.conf:
lrwxrwxrwx 1 root root 27 Jul 28 2020 /etc/resolv.conf -> /run/resolvconf/resolv.conf

both the "/etc/resolv.conf" and "/run/resolvconf/resolv.conf" are in red text on a grey background.


The results of cat /run/systemd/resolve/stub-resolv.conf:
cat: /run/systemd/resolve/stub-resolv.conf: No such file or directory

This seems to be your problem. Somehow systemd & resolved are not properly populating that file so you have no functional dns.

Try "systemctl status systemd-resolved.service" and post the output.

Also, please use code tags when you post the output of commands so we can see it exactly as formatted on your screen.

Here are the results of systemctl status systemd-resolved.service:

Hi all:
Sorry for the long delay in responding. My company has given me another laptop to work from so the one with problems could be entirely rebuilt with Ubuntu 20.10. All is now working correctly on all networks.
Thanks for all the help!
J