Hi!
I connected the router with the serial cable but when I type "tpl" to stop the boot nothing happens.
This is the message that appears:

U-Boot 1.1.4 (Sep  3 2010 - 12:15:38)

AP81 (ar7100) U-boot
DRAM:  
sri
32 MB
id read 0x100000ff
flash size 4MB, sector count = 64
Flash:  4 MB
Using default environment

In:    serial
Out:   serial
Err:   serial
Net:   ag7100_enet_initialize...
No valid address in Flash. Using fixed address
bsingle_phy = 0
eth0: 00:03:7f:09:0b:ad
eth0 up
eth0
Autobooting in 1 seconds## Booting image at bf020000 ...
   Uncompressing Kernel Image ... Error: inflate() returned -3
GUNZIP ERROR - must RESET board to recover

Resetting...[00]

I've tried 3 different programs: Putty, Termite and Serial Communicator.
Any suggestion?

The wiki mentions to short two pads of R356, did you do that?

Yes, I did.
If I do not weld this part, I do not get information on the console.
But I did not use the VCC.

The wiki also mentions this for your case:
If you successfully receive router bootup logs but seem unable to send data (e.g. some keyboard input which might be required to intercept bootup, and where you're unable to stop continued kernel bootup), then this may be due to having configured the connection as hardware flow control rather than software (happened on TL-WDR3600 in my case).

With some routers and some cables, people were successful when putting a pull-up resistor (between 2.2kOhms and 10kOhms) between the routers Rx and Vcc. This would boost the signal levels.

Also, a quick echo test of the cable could help to mitigate possible problems of the cable. Therefor, you would connect only your cables Tx to its Rx, nothing else. Then in your console program, disable local echo (meaning, that it should not print to screen which characters you send out; only output the data you receive) and type something. If your cable works, then you would see the characters you type in on screen.