Manage WLAN, LAN, WWAN and WAN subnets and routing table in the UI

[navado]

Is your feature request related to a problem?

When using with a board with multiple network interfaces it's annoying that routing between them and the access point needs to be configured in the system and not in the same place with the hostapd.
While it's possible to configure DHCP for all the interfaces, routing table might be tricky and not supported in the UI.

Describe the solution you'd like

UI section with ability to edit routing table and subnets, assign subnets to interfaces, etc.

Describe alternatives you've considered

It's possible to configure using command line of the host, write startup scripts etc, but not convenient when using such a nice and great tool like RaspAP

Additional context

For example with a board that has several separate ETH interfaces, LTE modem and WLAN it's reasonable to configure 1 LAN interface as WAN as default GW when connected, then WWAN as backup default GW, then LAN and WLAN as routable subnets both between them, VPN connections, etc.

In many network equipment vendors it's usual to create subnets (phisical or virtual) and then assign them to interfaces, configure routing between them, VPN connections etc.