IPadOS with Mullvad exit node experiences the "Magicsock" issue

### What is the issue?

All connectivity, tailnet and otherwise seems dead. Intermittent.

### Steps to reproduce

Use tailnet while connecting through a Mullved exit node. Eventually, connectivity to internet and other nodes stops working.

### Are there any recent changes that introduced the issue?

Mullvad exit nodes and tail lock. AFAIK I signed **all** Mullvad exit nodes.

### OS

iOS

### OS version

27dev beta

### Tailscale version

1.102.3

### Other software

_No response_

### Bug report

_No response_

Start by reproducing the intermittent connectivity failure on iOS 27 beta with Tailscale 1.102.3, a Mullvad exit node, and tail lock enabled. Gather a bug report when connectivity to the internet and other tailnet nodes stops working, then trace the Magicsock behavior involved. Done means connectivity remains available or the failure has a verified fix and regression coverage.

Written by the indexing model from the issue text.