Hi,I'm new in this forum
I have an Openwrt Router connected at Internet and a new Openwrt Router that I would connect at the first via ethernet and share connection on wifi.
How can I do it?

Look for "dumb AP recipe".

Bridging the two LAN interfaces with an Ethernet cable is generally sufficient, once you make sure that you don't have services that are "fighting each other" on the two routers. For example, the interfaces need to have different IP addresses and you probably only want one DHCP server and DNS server running.

I tried it,but it didn't work for me...

Configuration via Web Interface LUCI

Of course you can achieve this with using the web interface:
Once you have configured your wireless network with LUCI you can start configuring your dumb AP.

    Go to Network → Interfaces and select the Lan interface.
    Set an IP next to your main router on the field "IPv4 address". (If your main router has IP 192.168.1.1 set 192.168.1.2)
    Then scroll down and select the checkbox "Ignore interface: Disable DHCP for this interface."
    In the top menu go to System, then Startup, disable Firewall in the list of startup scripts.
    Click the Save and Apply button. Hard-Restart your router if you're not able to connect anymore.
    Now connect to the new IP you have just specified(192.168.1.2) and check if the settings for the Lan interface are the same you set before.
    Now connect your main router to one of the switch ports of your "new" dumb AP and you are done.

"it didn't work for me" does not give us much info about what went wrong...

In startup menu I disabled dnsmasq,firewall and odhcpd,too

Sorry, when I do ping to 192.168.1.1 I have this message: From 192.168.1.2 icmp_seq=1 Destination Host Unreachable

(Last edited by marcorm96 on 21 Feb 2018, 21:15)

Are both routers connected using an ethernet cable, plugged into the LAN port on both ends?

Each router has 4 Lan ports and I tried all combinations