iOS 1.68.0 lost dns with exit node enabled..

### What is the issue?

tl:dr; disable use as exit node to get dns working..

tailscale as road warrior setup.. just connecting back to the residence when on mobile data..

iOS, 17.4.1 messing with dns on a machine 100.75.66.53.. recently the iphones stopped showing up in the logs.. toggled, changed, etc, in tailscale.. using the same machine as an exit node..

dns leak test showed some res730.ord.rrdns.pch.net, res761, and res762 as the recursors.. when on mobile data with verizon.. after doing anything and everything to try and see my dns data appear in tailscale.. I had to *log out* and *log back in* to my tailnet to get the dns settings to work with my server settings..

Signing out does disable the exit node.. which is the odd part.. with the exit node disabled I would see all dns.. with exit node enabled.. it seems I lose dns..

there was no way to tell it wasn't working with my settings..

vpn was connected all tailscale settings looked enabled

Seems to be pretty reproduceable.. 1.68.0

Anyone else?

### Steps to reproduce

above..

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

_No response_

### OS

iOS

### OS version

17.4.1

### Tailscale version

1.68.0

### Other software

_No response_

### Bug report

BUG-8bd80029c5bac9223fe518d4d4022b1e4c8fbde81af55a30881f8a6a23eb7ad5-20240614202337Z-b256d704e779c48e