this problem seems to come in a lot of different flavors.
With my Ubuntu 18.04.3 LTS I can rarely use public Wifi because I cannot connect to the captive portal to login/"click connect".
In the KDE Networks tab I can connect to such a public wireless network.
It shows as connected in the tab (Wifi symbol, no little question mark).
However, I cannot resolve anything in the public Wifi network.
If I type anything into chromium, chrome, or firefox I get DNS_PROBE_FINISHED_NO_INTERNET.
curl looks like this...
curl -v google.com
* Rebuilt URL to: google.com/
* Could not resolve host: google.com
* Closing connection 0
curl: (6) Could not resolve host: google.com
...ping like this.
ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
^C
--- 8.8.8.8 ping statistics ---
22 packets transmitted, 0 received, 100% packet loss, time 21325ms
Everything works without issues on an iPhone, an Android, and a Windows10.
Before you mark this as duplicate; I have found the solutions mentioned below. Unfortunately none of them worked for me. They appear in different threads but I think there are essentially 4:
- reboot NetworkManager or machine
- alternative DNS servers (also mentioned here)
- systemd-resolved main dns=default
- connect to default gateway
ifconfig
wlp3s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 10.23.105.183 netmask 255.255.254.0 broadcast 10.23.105.255
inet6 fe80::e275:f0ba:2953:9649 prefixlen 64 scopeid 0x20<link>
ether b4:6d:83:cd:7e:9a txqueuelen 1000 (Ethernet)
RX packets 50246 bytes 14090564 (14.0 MB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 35844 bytes 5616976 (5.6 MB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
systemd-resolve --status
Global
DNS Servers: 8.8.8.8
DNSSEC NTA: 10.in-addr.arpa
16.172.in-addr.arpa
168.192.in-addr.arpa
17.172.in-addr.arpa
18.172.in-addr.arpa
19.172.in-addr.arpa
20.172.in-addr.arpa
21.172.in-addr.arpa
22.172.in-addr.arpa
23.172.in-addr.arpa
24.172.in-addr.arpa
25.172.in-addr.arpa
26.172.in-addr.arpa
27.172.in-addr.arpa
28.172.in-addr.arpa
29.172.in-addr.arpa
30.172.in-addr.arpa
31.172.in-addr.arpa
corp
d.f.ip6.arpa
home
internal
intranet
lan
local
private
test
...
Link 3 (wlp3s0)
Current Scopes: DNS
LLMNR setting: yes
MulticastDNS setting: no
DNSSEC setting: no
DNSSEC supported: no
DNS Servers: 8.8.8.8
DNS Domain: ~.
client.m3-hotspots.de
...
Update
I was on a German train again and as commented by waltinator I tried to curl and ping detectportal.firefox.com after adding 184.150.154.24 detectportal.firefox.com to /etc/hosts. ping didn't go through and curl returned 302 not found. I watched journalctl -f /usr/sbin/NetworkManager while trying to connect.
Dez 23 14:00:35 uranus NetworkManager[878]: <info> [1577106035.2216] manager: NetworkManager state is now CONNECTED_LOCAL
Dez 23 14:00:35 uranus NetworkManager[878]: <info> [1577106035.2285] manager: NetworkManager state is now CONNECTED_SITE
Dez 23 14:00:35 uranus NetworkManager[878]: <info> [1577106035.2286] policy: set 'WIFIonICE' (wlp3s0) as default for IPv4 routing and DNS
Dez 23 14:00:35 uranus NetworkManager[878]: <info> [1577106035.2308] device (wlp3s0): Activation: successful, device activated.
Dez 23 14:00:35 uranus NetworkManager[878]: <info> [1577106035.2317] manager: NetworkManager state is now CONNECTED_GLOBAL
(no new log appeared while trying to connect)
However, the 302 response header looked like this:
Connection: close
Content-Length: 0
Date: Mon, 23 Dec 2019 13:08:28 GMT
Location: http://www.wifionice.de/de/?url=http%3A%2F%2Fdetectportal.firefox.com%2F
Server: squid
Via: 1.1 IMP-redirect (squid)
X-Cache: MISS from IMP-redirect
X-Cache-Lookup: MISS from IMP-redirect:3129
www.wifionice.de was the captive portal on that train.
When opening detectportal.firefox.com in chromium I can see that the redirect to http://www.wifionice.de/de/?url=http%3A%2F%2Fdetectportal.firefox.com%2F is done, but the request to www.wifionice.de doesn't return.
Curl returns this:
curl -v http://www.wifionice.de/de/?url=http%3A%2F%2Fdetectportal.firefox.com%2F
* Could not resolve host: www.wifionice.de
* Closing connection 0
curl: (6) Could not resolve host: www.wifionice.de
