Ok I made it!
For everyone who wants to know how how I did it is was:
1) Completely disabled DHCP on Router B. This can be done by ssh or by luci.
Final configuration is:
config 'dnsmasq'
option 'domainneeded' '1'
option 'boguspriv' '1'
option 'filterwin2k' '0'
option 'localise_queries' '1'
option 'rebind_protection' '1'
option 'rebind_localhost' '0'
option 'local' '/lan/'
option 'domain' 'lan'
option 'expandhosts' '1'
option 'nonegcache' '0'
option 'authoritative' '1'
option 'readethers' '1'
option 'leasefile' '/tmp/dhcp.leases'
option 'resolvfile' '/tmp/resolv.conf.auto'
2) Disable Firewall and DNSMASQ. This can be done via luci-app-initmgr or by ssh
root@OpenWrt2:~# /etc/init.d/dnsmasq disable
root@OpenWrt2:~# /etc/init.d/firewall disable
3) configure LAN for DHCP and configure default dns server (for internet access directly on router B, for example: opkg update)
The dns server ip is the ip of router A
config 'interface' 'lan'
option 'ifname' 'eth0.1'
option 'type' 'bridge'
option 'defaultroute' '0'
option 'peerdns' '0'
option 'dns' '192.168.1.1'
option 'proto' 'dhcp'
And now Router B is ready.
Bridge Magic will happen and all packets will be directly send to router A. Everything. Just like you're directly connected to router A-
Now, on router A I did the following:
A) Make a DHCP reservation for router B
/etc/config/dhcp
config 'host'
option 'name' 'OpenWrt2'
option 'mac' '94:0c:6d:ee:80:1e'
option 'ip' '192.168.1.2'
This is easier to do with luci.
B) Configure everything else on Router A like it is your only router.
C) Router A in this example is 192.168.1.1, router B is 192.168.1.2 and the wired/wireless clients are from 192.168.1.100 (default config on openwrt)
This learned and notes:
- LAN bridge is *faster* than creating a wan to lan bridge on router B. And simpler to do
- Configuring time, hostname, luci, etc and extra packages or features of OpenWRT is omitted here
- Everything works very easily by this way. Almost no configuration needed.
- Both routers have same SSID on different channels. This makes roaming possible if client/server supports it and its simpler for clients to connect automatically to strongest router