Ii all,
I have a converter usb serial based on ft232rl it has 4 male pins gnd, +5v, tx, rx
Is it possible to use it to upload a sketch over arduino ethernet intead using usb2serial light or ftdi cable ?
Yes, it is possible. Connect GND to the pin labelled BLK, leave the next pin unconnected, next pin 5V, then TX and next RX. The last one is the reset line (normally connected to DTR), as you don't have that line you have to reset the Arduino manually by pressing the reset button immediately before you upload your sketch.
On the Arduino you won't see any LED blink during transfer but on my USB2Serial Light both, RX and TX, blink more or less at the same time during the transfer to the Arduino Ethernet.
Can you make a photo of your wiring and post it here?
Edit: Did you remember to reset the Arduino manually shortly before you upload the sketch?