How to setup openwrt wifi client?

Question

Computer networks

There are two routers on openwrt. I'll call them 1 and 2.
1 - distributes wifi SSID (Openwrt)
2 - the task is to connect it to this wifi network from the first one.
So. I carried out all the actions on the second router through LUCI. First, I demolished all valid wifi profiles. Then I pressed the Scan button, selected the wifi network of the first router, entered the password and then connected it. Router 1 issued router 2 ip. However, from wifi network 1, I could not connect to router 2 using the given ip. Then I changed the subnet mask for the LAN interface in router 2 and a miracle, now from wifi router 1 I can hack myself to router 2.
Then I went to the Diagnostics item and pinged Google.com. Writes that Bad Hostname. Now pinged 8.8.8.8 - everything is fine pinged. That is, now my router 2 pings to external ip, but when I enter a domain there, it says that it does not know such a host.
Here I got up. So router 1 is to blame for not providing dns. But other clients, such as a tablet, normally respond to everyone. What's wrong?
UPD1
Cured by adding extra. DNS - 8.8.8.8. The question is, why, for example, did you not have to do this in a tablet?

Answer 1

Tablet - received an address via DHCP (ie address, route and dns).
Router - configured statically (manually), respectively, he knew nothing about DNS.

Answer 2

Because you need to add to the /etc/config/network file:
config interface wwan
option proto 'dhcp'