Isolated Local Network Issues

### ⚠️ Before posting ⚠️

- [x] This is a **bug**, not a question or an enhancement.
- [x] I've [searched for similar issues](https://github.com/nextcloud/android/issues) and didn't find a duplicate.
- [x] I've written a clear and descriptive title for this issue, not just "Bug" or "Crash".
- [x] I agree to follow Nextcloud's [Code of Conduct](https://nextcloud.com/contribute/code-of-conduct/).

### Steps to reproduce

1. Have a router without a WAN connection
2. Connect server to it
3. Setup nextcloud on that server
4. Setup DNS server on said server pointing to nextcloud
5. Setup android phone to connect to router
6. set the server as the dns server
7. setup nextcloud to the local domain via local dns
8. Try to upload any files

### Expected behaviour

NextCloud uploads the files over the LAN

### Actual behaviour

NextCloud refuses to upload, and will only upload when connected to a WAN.

### Android version

15

### Device brand and model

OP8T

### Stock or custom OS?

Custom (explain in "additional information")

### Nextcloud android app version

3.31.1

### Nextcloud server version

stable

### Using a reverse proxy?

Yes

### Android logs

_No response_

### Server error logs

```bash

```

### Additional information

LineageOS.

Stable build.