Several ways to check where your LilyGO board is connected on Ubuntu

 1. Use lsusb to list USB devices

 

2. Check /dev/tty* devices

ls /dev/ttyUSB* /dev/ttyACM* 2>/dev/null

3. Use dmesg to see connection messages
dmesg | tail -20

 

4. List all serial devices with details 

ls -la /dev/serial/by-id/