wifi hotspot doesn't work when VPN is connected

for some reason `generate_random_ip4()` inside of this script stales when you are connected to the VPN. i don't know why, maybe because `is_ip4_lan_range_available $random_ip4 && break` loops and can't find available ip address.

solution is to specify gateway manually:

```bash
sudo lnxrouter -g 10.0.0.1 --ap wlp1s0 <ssid> -p <password>
```