I had a simple piece of code with UITEthernet. Just blink a LED in port 13. I went on uploading the code to Arduino Nano. The IDE told that it is not possible. In Tools the Port had disappeared. USB memory stick worked OK. In Linux terminal lsusb gave no connection.. In /dev there was no ttyUSBx, and dmesg gave this over and over:
[ 2470.432740] usb 1-2: new full-speed USB device number 29 using xhci_hcd [ 2470.544882] usb 1-2: Device not responding to setup address. [ 2470.748941] usb 1-2: Device not responding to setup address. [ 2470.953111] usb 1-2: device not accepting address 29, error -71
I changed Arduino Nano and agoin to the third, Same problem. No usefull help from Google.
Then I took the USB connector out,in,out,in,out,in as fast as I could. Now all my Arduinos work again.