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#11142·mullvadvpn-app

Custom DNS doesn't actually update system DNS

Author: fynnayCreated Sep 13, 2026Updated Sep 15, 2026
LabelsbugLinux

Is it a bug?

  • I know this is an issue with the app, and contacting Mullvad support is not relevant.

I have checked if others have reported this already

  • I have checked the issue tracker to see if others have reported similar issues.

Current Behavior

Setting Mullvad custom DNS doesn't set the specified one in /etc/resolv.conf

Expected Behavior

Setting Mullvad custom DNS updates /etc/resolv.conf accordingly.

Steps to Reproduce

  1. Run mullvad dns set default
  2. Run cat /etc/resolv.conf
    • nameserver 10.64.0.1
    • Great. This seems to be working.
  3. Run mullvad dns set custom 192.168.0.44
  4. Run cat /etc/resolv.conf
    • nameserver 192.168.0.2 <- this is an old, now decommissioned DNS server
    • nameserver 9.9.9.9 <- don't know where this is coming from

Failure Logs

bash
sep 13 18:06:42 Pengling mullvad-daemon[856]: DEBUG mullvad_daemon::management_interface: set_dns_options(DnsOptions { state: Default, default_options: DefaultDnsOptions { block_ads: false, block_trackers: false, block_malware: false, block_adult_content: false, block_gambling: false, block_social_media: false }, custom_options: CustomDnsOptions { addresses: [192.168.0.44] } })
sep 13 18:07:42 Pengling mullvad-daemon[856]: DEBUG mullvad_daemon::management_interface: get_settings
sep 13 18:07:42 Pengling mullvad-daemon[856]: DEBUG mullvad_daemon::management_interface: set_dns_options(DnsOptions { state: Custom, default_options: DefaultDnsOptions { block_ads: false, block_trackers: false, block_malware: false, block_adult_content: false, block_gambling: false, block_social_media: false }, custom_options: CustomDnsOptions { addresses: [192.168.0.44] } })
sep 13 18:07:42 Pengling mullvad-daemon[856]: DEBUG mullvad_daemon::settings: Writing settings to /etc/mullvad-vpn/settings.json
sep 13 18:07:42 Pengling mullvad-daemon[856]: DEBUG mullvad_daemon::management_interface: Broadcasting new settings
sep 13 18:07:42 Pengling mullvad-daemon[856]:  INFO talpid_core::firewall: Applying firewall policy: Connected to { 45.129.56.67:5825/UDP } over "wg0-mullvad" (ip: 10.147.105.181, v4 gw: 10.64.0.1, v6 gw: None), Allowing LAN
sep 13 18:07:42 Pengling mullvad-daemon[856]:  INFO talpid_dns: Setting DNS servers: Tunnel DNS: {} Non-tunnel DNS: {192.168.0.44}
sep 13 18:07:42 Pengling mullvad-daemon[856]: DEBUG talpid_dns::imp: Can't manage DNS using systemd-resolved: systemd-resolved operation failed
sep 13 18:07:42 Pengling mullvad-daemon[856]: DEBUG talpid_dbus::network_manager: /etc/resolv.conf differs from reference resolv.conf, therefore NM is not managing DNS
sep 13 18:07:42 Pengling mullvad-daemon[856]: DEBUG talpid_dns::imp: Can't manage DNS using NetworkManager: NetworkManager is not managing DNS
sep 13 18:07:42 Pengling mullvad-daemon[856]: DEBUG talpid_dns::imp: Can't manage DNS using resolveconf: The resolvconf in PATH is just a symlink to systemd-resolved
sep 13 18:07:42 Pengling mullvad-daemon[856]: DEBUG talpid_dns::imp::static_resolv_conf: No DNS state backup to restore
sep 13 18:07:42 Pengling mullvad-daemon[856]: DEBUG talpid_dns::imp: Managing DNS via /etc/resolv.conf

Operating system version

linux 7.2.4-arch1-2 (64-bit) - endeavouros

Mullvad VPN app version

2026.4

Additional Information

Despite what the LOG says, there is in fact a backup here: resolv.conf.mullvadbackup, which is created when disabling custom DNS in mullvad - the file contains the faulty entries. Even when I delete this file and then set custom DNS again, those faulty entries still end up in /etc/resolv.conf.

Source: mullvad/mullvadvpn-app

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