I have a Pi 3 that’s been running PiAware for a number of years, and been updated/upgraded over the years. It’s been running reliably and stays up and accessible for months with no issues, but only recently, somewhat randomly, it started becoming unreachable on my local wifi.
Since it’s running headless, I don’t normally have a screen or keyboard attached to it, and if I need to access it then I ssh into it over wifi. Without ssh access I was kind of in the dark what was going on. The power and activity lights were still on/flickering, so I knew it hadn’t crashed completely.
I remembered I had a USB/Serial cable in my box of cables somewhere, but had actually not used it since Pi 1 days, so looked around for the correct steps to connect it.
For a diagram of what colour connectors to connect to what GPIO pins, see: https://www.jeffgeerling.com/blog/2021/attaching-raspberry-pis-serial-console-uart-debugging
List serial connections over USB:
ls /dev | grep usb
For me this shows:
❯ ls /dev | grep usb cu.usbserial-11240 tty.usbserial-11240
To connect with screen:
screen /dev/tty.usbserial-11240 115200
To exit, type Ctrl-A then Ctrl-D (from here)
To connect with minicom:
minicom -b 115200 -D /dev/tty.usbserial-11240
Esc then X to exit.