IP inicial 192.168.3.1 and DHCP server disabled, when the default should be 192.168.1.1. Found without resetting, creating a Shared Wired Connection in Kubuntu and connecting it to the WAN port, to later see the address assigned to the router in syslog and open it in the browser (Even though the router interface should not be accessible by WAN!).
To use it as a repeater, it only supports WDS bridge mode. Unable to connect to a TP-Link WR-740N.
Only Asus router that doesn't support any of the major open firmwares? OpenWRT tiene preliminary support.
ASUS RT-N56U/RT-N65U custom firmware not bad. Russian, Based on OpenWRT?
Add mode “AP + customer AP”, but it doesn't work with the WR-740N either.
Time to change the WR-740N to something better. DD-WRT is a daemon slaughter and overall disaster. OpenWRT + LuCi works great, but there are only 100 free kB. Gargoyle, its rebellious and minimalist scion, works just as well and lets 400 kB (!)–except that after flashing it did not activate DHCP or wireless; a little worrying until you do ssh root@192.168.1.1 and you see that everything works.
OpenWRT also adds “AP + customer AP” al TP-Link, and now both routers work seamlessly as master or client. Aaaah… life is a boat.