Hello guys, I am using a TP-LINK TL-WR740N and in this morning after a long period of problems with it ( it gave me limited connectivity all the time ) I decided to do something about it.
              First I wanted to upgrade firmware, but I got an error code 18005.
After that I saw something about OpenWRT and decided to try it. After that, I've noticed that my configuration was gone, so i had to reconfigure it. I reconfigured the WAN with PPPoE and i think here i did something wrong, i changed the LAN to PPPoE too.
             Now i cannot access it. If i use Ethernet through router i got unidentified network and if i try to access router via browser, it shows like i want to connect to any other site so i got error message that i am not connected to internet. Same thing if i try to use WI-FI with the difference that when i connect i have to try 3-5 times and after i get connected to router, i got limited connection and same problem.
            Any idea is good. Thanks in advice.

http://wiki.openwrt.org/doc/howto/generic.failsafe

remember to set a static ip on NIC

I am unable to put my router in failsafe. I dont know how to change my id address to 192.168.1.2 to 254. And what NIC means? Thanks in advice.

I also run recvudp.exe for entering failsafe. I run TP-LINK easy setup assistant and it said 'make sure ur router DHCP Server is Enabled'. How do i check or how do i enable it? Also if this help you, LED config is the next one:
PWR LED is permanently lit
SYS LED blink about 2 times/sec
If I connect laptop to router the LED for 1,2,3 or 4 is permanently lit. Now i am bypassing router to access the internet. Any other idea? Thanks in advice.