I need to configure my openwrt router and bridge wlan connection to lan, as shown below:
Basically, my solar system creates it's own wlan access-point with a webpanel, but has no eth ports so I need to be connected over wifi. I want to connect my openwrt router to this access-point as a client and bridge/forward it via LAN cable to my main router, having my solar system's webpanel accesible from all the other devices on main router. Is this possible?
Openwrt device: TP-LINK TL-WR850N V2
It's gonna be placed directly near the solar system. The LAN cable goes from there to my house, connected to my main router. The distance is too big for a direct wireless connection, that's why I need to use a cable.
That's what I need:
Possible, yes, but not without side-effects, which would need careful consideration.
The problem here is, that the STA (client-) interface takes precedence over concurrent AP interface, meaning it needs to connect to your solar AP first, before it in turn can provide its own AP interfaces for your normal WLAN clients to work. If -for whatever reason- this STA connection cannot be established, the AP interfaces of your router will never come up.
Bridging, no - routing a different subnet, yes.
 on most OpenWrt supported router hardware, but not all
 for this specific case, it might make sense to attach a USB WLAN card to your router, to act as dedicated client interface of your solar AP and leaving the integrated radios of your router alone, keeping them free to do provide your wifi SSID
 with its own firewall zone and appropriate settings
The hardware is a TP-LINK TL-WR850N V2 router.
It's gonna be placed directly near the solar-system AP, outdoors. The LAN cable goes from there to my house, connected to my main router indoors. The problem is, my solar system does not have an ethernet port, so the openwrt router acting as a client needs to be connected on the other side, between the main router and solar-system AP.
The distance is too big for a direct wireless connection, that's why I need to use a cable. USB WLAN card won't work in this case.