adb: no devices/emulators

UgurY

I have a Rockchip iCore3588Q

When i press and hold recovery button while powering the device about 2 seconds. After this

The device mode looks Loader, but i cant see on adb devices or adb shell.
Why i cant see the device on adb ? My host pc is ubuntu 20.04.

UgurYakut

I am new to these boards, and I don’t know how to connect them. I am trying to find the IP address by connecting to the board via Ethernet. To find the board’s IP address, I run the 'arp -a' command in the Windows command prompt, but the board’s address does not appear. I can see messages from the board through the serial port, and it seems to be starting up, but I cannot find its IP address