Cannot use many public Wifi using Ubuntu 18.04

Question

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