Networking broken with WSL2 and Windows 11 when using networkingMode=mirrored

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### Windows Version

Microsoft Windows [Version 10.0.22631.5768]

### WSL Version

2.5.10.0

### Are you using WSL 1 or WSL 2?

- [x] WSL 2
- [ ] WSL 1

### Kernel Version

Linux version 6.6.87.2-microsoft-standard-WSL2 (root@439a258ad544) (gcc (GCC) 11.2.0, GNU ld (GNU Binutils) 2.37) #1 SMP PREEMPT_DYNAMIC Thu Jun 5 18:30:46 UTC 2025

### Distro Version

Ubuntu 24.04

### Other Software

_No response_

### Repro Steps

PS> wsl
$ ping 8.8.8.8
ping: connect: Network is unreachable
$ ip addr show
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
inet 10.255.255.254/32 brd 10.255.255.254 scope global lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
$ curl www.google.com
curl: (6) Could not resolve host: www.google.com

### Expected Behavior

Ping works and there is output showing HTML/CSS/JavaScript code from the curl command.

### Actual Behavior

See repro steps above.

### Diagnostic Logs

[WslNetworkingLogs-2025-09-05_16-49-33.zip](https://github.com/user-attachments/files/22181263/WslNetworkingLogs-2025-09-05_16-49-33.zip)

Start by reproducing the failure in WSL2 on Windows 11 with networkingMode=mirrored, then inspect the attached WslNetworkingLogs archive alongside the reported ip addr, ping, and curl results. Done means the Ubuntu instance has working network connectivity, ping to 8.8.8.8 succeeds, and curl www.google.com returns HTML/CSS/JavaScript output.

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