[systemd-devel] Problems with DNS resolution in German Rail WiFi

[Paul Menzel]

Dear systemd folks,


Since over half a year, I am having problems with the German Rail WIFI 
(Deutsche Bahn, WIFIonICE) [1]. I am only having problems with the WIFI 
in the train. The WIFI on the train stations (operated by Deutsche 
Telekom(?)) works fine.

I am able to connect to the WIFI network, but accessing the capture page 
to log in, and after logging in, I am having serious DNS problems in the 
browsers (Mozilla Firefox 70.0 and Google Chromium). I am using Debian 
Sid/unstable.

It looks like that, DNS requests are not answered in time (also 
confirmed by the developer tools in the browser). SSH (and even Mozilla 
Thunderbird) seems to work better. The fellow train travelers do not 
seem to have any problems.

Testing on the console shows:

```
$ time host bahn.de
bahn.de has address 18.185.205.203
bahn.de has address 35.157.56.133
bahn.de has address 35.158.56.207
bahn.de mail is handled by 10 mailgate2.deutschebahn.com.
bahn.de mail is handled by 10 mailgate1.deutschebahn.com.

real	0m0,243s
user	0m0,021s
sys	0m0,000s
$ systemd-resolve bahn.de
bahn.de: resolve call failed: Die Wartezeit für die Verbindung ist 
abgelaufen
$ time systemd-resolve bahn.de
bahn.de: resolve call failed: DNSSEC validation failed: failed-auxiliary

real	0m55,967s
user	0m0,006s
sys	0m0,006s
$ time systemd-resolve bahn.de
bahn.de: resolve call failed: Die Wartezeit für die Verbindung ist 
abgelaufen

real	2m0,094s
user	0m0,005s
sys	0m0,007s
$ time systemd-resolve bahn.de
bahn.de: resolve call failed: Die Wartezeit für die Verbindung ist 
abgelaufen

real	2m0,113s
user	0m0,014s
sys	0m0,000s
```

How can this be debugged (next time I am using the ICE)? Is this 
systemd-resolved related? If not, who should I bug about it?


Kind regards,

Paul


[1]: https://www.bahn.de/p/view/service/zug/railnet_ice_bahnhof.shtml