ipn/ipnlocal: funnel stops working after tailscaled stays offline for too long

### What is the issue?

I had funnel set up on my machine and it worked fine until I lost power for about 40 hours. When the power came back, I could reach the service over the tailnet fine but not over funnel. I had to turn funnel off, wait a minute and turn it back on again for it to start working again.

```
... failed to post request: Post "https://.tail-net.ts.net/...": EOF
```

Machine restarted at `2024-11-21T17:50:55Z`, disabled funnel at `2024-11-21T18:25:00Z`, reenabled funnel at `2024-11-21T18:26:09Z`

### Steps to reproduce

_No response_

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

_No response_

### OS

Linux

### OS version

ubuntu 24.04

### Tailscale version

1.77.33

### Other software

_No response_

### Bug report

BUG-52b20aff21cf003dad7cd9c3c3cf6dc65ca6fa4f1535f46692ea3a0181a0fbe0-20241121192818Z-f9084c0c2262c0a2