During a recent trip on a Deutsche Bahn (ICE) train, I was unable to properly use the onboard WiFi.

I could connect to the WiFi network itself, but I never received the captive portal (login page), and I had no internet access.

What I tried

1. Manually opening the login page:

• https://login.wifionice.de
  → did not load

2. Trying IP addresses mentioned in forums that supposedly redirect to the login page
   → no success

3. Testing connectivity:

ping 1.1.1.1  
ping 8.8.8.8

→ no responses

4. Checking for subnet conflicts (e.g., Docker vs WiFi):
   • I read that overlapping subnets can cause issues
   • My Docker and WiFi networks do not overlap (see ip a output below)

System details

• Device: Framework Laptop
• OS: Fedora 40
• Network tools: standard Linux networking stack

ip a output

1: lo:  mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host noprefixroute 
       valid_lft forever preferred_lft forever
2: wlp1s0:  mtu 1440 qdisc noqueue state UP group default qlen 1000
    link/ether 26:54:c0:49:9b:38 brd ff:ff:ff:ff:ff:ff permaddr 78:46:5c:01:25:55
    altname wlx78465c012555
    inet 172.18.79.44/16 brd 172.18.255.255 scope global dynamic noprefixroute wlp1s0
       valid_lft 238sec preferred_lft 238sec
    inet6 fe80::f233:5bd1:bee3:6c15/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
3: br-8fdfc4dd458c:  mtu 1500 qdisc noqueue state DOWN group default 
    link/ether d2:c6:81:16:0c:70 brd ff:ff:ff:ff:ff:ff
    inet 172.18.0.1/16 brd 172.18.255.255 scope global br-8fdfc4dd458c
       valid_lft forever preferred_lft forever
    inet6 fe80::d0c6:81ff:fe16:c70/64 scope link proto kernel_ll 
       valid_lft forever preferred_lft forever
4: docker0:  mtu 1500 qdisc noqueue state DOWN group default 
    link/ether 16:33:ca:56:13:98 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
       valid_lft forever preferred_lft forever
5: br-1c677e576207:  mtu 1500 qdisc noqueue state DOWN group default 
    link/ether da:e5:e0:b8:9f:4b brd ff:ff:ff:ff:ff:ff
    inet 172.19.0.1/16 brd 172.19.255.255 scope global br-1c677e576207
       valid_lft forever preferred_lft forever

Question

What could prevent the captive portal from appearing and block all traffic in this situation?

Any debugging tips or things I should try next would be greatly appreciated.

I'm still relatively new to networking, but I'm happy to dig deeper and learn.

Thanks!