after takin a look at the routes, i guess i have to set a static route for 0.0.0.0/0 on lan
edit: that did it, my bad
edit2: that only worked until a reboot.. now its back to routing over nvr, the static route is still set in configuration, but under status there is a route over nvr only, any idea ?
By default, OpenWrt expects Internet access to be routed to a WAN such as a modem. Main thing to look out for there is that the WAN network can't be the same IP subnet as the LAN. If you have static IP the WAN you need to explicitly set gateway and DNS in the wan config, if it is DHCP or pppoe it will auto configure.
If you are connected to the Internet through the LAN network as a LAN device of another router, you need to add option gateway and option dns to the LAN configuration. And the LAN network needs to be the same IP subnet as the main network.
In that use case, the IOT interfaces should be "unmanaged" so that the OpenWrt kernel does not hold an IP address on them at all. Your IOT devices bridge through them at layer 2 and the main router handles all of their layer 3 stuff. OpenWrt here acts only as a wired to wifi converter and / or Ethernet switch.
Then OpenWrt will use the lan which is usually a more privileged network in the main router.