To configure OpenWrt for 4 virtual networks (VLANs) on the 4 ports of the internal switch, you'll need to edit the network configuration file (usually found in `/etc/config/network`) and potentially the firewall configuration (in `/etc/config/firewall`) to secure the specified VLANs.
Below are the sample configuration snippets for your requirements:
### /etc/config/network
```bash
config switch
option name 'switch0'
option reset '1'