DNS SERVFAIL on Ubuntu 26.04 with kernel 7.0.0-15 — Mullvad DNS 10.64.0.1 fails to resolve

### Is it a bug? - [x] 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 - [x] I have checked the issue tracker to see if others have reported similar issues. ### Current Behavior Inhoud: **Mullvad version:** 2026.1 **OS:** Ubuntu 26.04 LTS (Resolute Raccoon) **Kernel:** 7.0.0-15-generic **Desktop:** GNOME on Wayland **Problem:** After upgrading from kernel 7.0.0-13 to 7.0.0-15, Mullvad's internal DNS server (10.64.0.1) returns SERVFAIL for all queries when connected to the VPN. **Steps to reproduce:** 1. Connect to Mullvad VPN 2. Run: dig @10.64.0.1 nl.archive.ubuntu.com 3. Result: status: SERVFAIL **Workaround:** Setting a custom DNS server (1.1.1.1) in Mullvad settings fixes the issue. **Additional info:** - DNS content blocking was disabled - The VPN tunnel itself works fine - Problem did not occur on kernel 7.0.0-13 ### Expected Behavior DNS queries should be resolved successfully when connected to Mullvad VPN, using the internal DNS server (10.64.0.1), without needing to set a custom DNS server as a workaround. ### Steps to Reproduce 1. ... 2. ..1. Install Ubuntu 26.04 LTS (Resolute Raccoon) with kernel 7.0.0-15-generic 2. Install Mullvad VPN 2026.1 3. Connect to any Mullvad VPN server 4. Disable all DNS content blocking in Mullvad settings 5. Run: dig @10.64.0.1 nl.archive.ubuntu.com 6. Observe: status: SERVFAIL — all DNS queries fail 7. Run: sudo apt update 8. Observe: "Temporary failure in name resolution" for all repositories Note: The issue did not occur on kernel 7.0.0-13. Workaround: set custom DNS to 1.1.1.1 in Mullvad settings. ### Failure Logs ```shell ``` ### Operating system version _No response_ ### Mullvad VPN app version _No response_ ### Additional Information _No response_