Upload to an old Ethernet Pro

I got some old(but new) Ethernet Pro that would fit perfect for a little project where i need an ethernet NTP server.
But i can’t manage to upload any code to the board. I use a generic USB-TTL RX/TX RST to DTR on the Ethernet Pro.
I tried several upload speeds (19200/57600/115200) but noting works. The USB-TTL adapter works, i use it to flash ESP’s.
I tried using Arduino IDE2.3 and platformIO. Same problem in both.
Anyone have any suggestions?

What board definition are you using?

Feels like i try them all, UNO, Mini/Pro, Nano, Ethernet, and probably a bunch more. It would be good to know what setup works for Atmega328 with optiboot.
I can see that the board reset when the programming is trying to start. The onboard led have a flash pattern, then it’s just stay dimmed. It’s like the PC side don’t get a response from board after reset is performed.

This board features the ‘Optiboot’ bootloader, so be sure to select “Arduino Uno” in the Arduino IDE when you program it <

I’m pretty sure Uno is the correct board def but you might also try the 5 volt arduino pro mini. I’d also recommend using a FTDI USB to serial adapter, you’re much less likely to have problems and that was the USB to serial interface this board was designed around.
DEV-09716 would be an excellent choice.

I had to give up using serial. I did use “Arduino As ISP” and that worked well.