Errors: does not resolve & "Login with nextcloud" does not find my local instance

[kreativkod]

I started getting synchronization errors between my local Nextcloud instance and my Android 14 phone about a week ago (I think, I haven't been paying too close attention). The error notifictions says "cannot resolve hostname: nextcloud.nibelheim".

The strange thing is that I have defined a host override for nextcloud.nibelheim in my pfsense DNS resolver (pfsense is my DNS server) and it works both on computers, laptops and on phones. When I type https://nextcloud.nibelheim in any browser on the phone it will resolve to the correct local IP address and take me to my local Nextcloud instance login screen. But DavX5 can't resolve it.

If I for troubleshooting purposes try to add a new account and select "Login with Nextcloud", DavX5 responds: couldn't obtain login URL. Neither direct IP address works which is even weirder.

What might be up with DavX5 not finding my local Nextcloud all of a sudden?

[rfc2822]

You can view the logs after an unsuccessful login and you should be able to find all details there.

DAVx5 uses okhttp, which uses the normal system methods for DNS resolving as far as I know.

[kreativkod]

Hi,
I am looking at the logs from DavX5 on my Pixel 7 / Android 14 and it says:

2024-04-25 00:16:17 2 [ui.setup.LoginTypeNextcloud] Couldn't obtain login URL
EXCEPTION java.net.UnknownHostException: Unable to resolve host "nextcloud.nibelheim": No address associated with hostname

That seems clear enough, but when I run a DNS lookup from the same phone the DNS lookup works fine.
What might I be missing:

[rfc2822]

What does the Connectivity section in DAVx5 debug info say?

[kreativkod]

CONNECTIVITY

 ☒ wlan0
   - [ Transports: WIFI Capabilities: NOT_METERED INTERNET NOT_RESTRICTED TRUSTED NOT_VPN VALIDATED NOT_ROAMING FOREGROUND NOT_CONGESTED NOT_SUSPENDED NOT_VCN_MANAGED LinkUpBandwidth>=102422Kbps LinkDnBandwidth>=115717Kbps TransportInfo: <SSID: <unknown ssid>, BSSID: 02:00:00:00:00:00, MAC: 02:00:00:00:00:00, IP: /10.0.1.20, Security type: 2, Supplicant state: COMPLETED, Wi-Fi standard: 6, RSSI: -64, Link speed: 576Mbps, Tx Link speed: 576Mbps, Max Supported Tx Link speed: 1200Mbps, Rx Link speed: 432Mbps, Max Supported Rx Link speed: 1200Mbps, Frequency: 5180MHz, Net ID: -1, Metered hint: false, score: 60, isUsable: true, CarrierMerged: false, SubscriptionId: -1, IsPrimary: -1, Trusted: true, Restricted: false, Ephemeral: false, OEM paid: false, OEM private: false, OSU AP: false, FQDN: <none>, Provider friendly name: <none>, Requesting package name: <none><none>MLO Information: , Is TID-To-Link negotiation supported by the AP: false, AP MLD Address: <none>, AP MLO Link Id: <none>, AP MLO Affiliated links: <none>> SignalStrength: -64 UnderlyingNetworks: Null]
   - DNS: fe80::ca7f:54ff:fee3:2820%wlan0, 10.0.1.1
 ☐ rmnet1
   - [ Transports: CELLULAR Capabilities: IMS NOT_METERED TRUSTED NOT_VPN VALIDATED NOT_ROAMING FOREGROUND NOT_CONGESTED NOT_SUSPENDED NOT_VCN_MANAGED MMTEL LinkUpBandwidth>=18000Kbps LinkDnBandwidth>=41323Kbps Specifier: <TelephonyNetworkSpecifier [mSubId = 1]> UnderlyingNetworks: Null]
   - DNS: 
 ☐ rmnet2
   - [ Transports: CELLULAR Capabilities: MMS SUPL INTERNET NOT_RESTRICTED TRUSTED NOT_VPN VALIDATED NOT_ROAMING NOT_CONGESTED NOT_SUSPENDED NOT_VCN_MANAGED LinkUpBandwidth>=18000Kbps LinkDnBandwidth>=41323Kbps Specifier: <TelephonyNetworkSpecifier [mSubId = 1]> UnderlyingNetworks: Null]
   - DNS: 2a02:aa0::56, 2a02:aa0::55, 80.251.201.178, 80.251.201.177

Data saver: disabled

[rfc2822]

Is this DNS server correct and do both the IPv4 and IPv6 DNS resolve the name correctly?

[kreativkod]

Thanks for the idea about IPv6.
Problem solved! (I think)
The Nextcloud instance at nextcloud.nibelheim did not have any IPv6 configured. Autoconfiguring that and rebooting firewalls (switching back and forth between old and current configs a few times) and devices seems to have solved the problem.
I also added the IPv6 address to the host override for nextcloud.nibelheim in pfsense.
Weird thing: ping IPv6 does not work, but DNS lookup resolves both IPv4 & 6
/ fingers crossed /