Just a quick note about a Raspberry Pi Zero that has become unresponsive over SSH.

The Pi Zero 2 W I used for the smart mirror project started exhibiting this symptom. I’d try to log in over SSH, enter my password at the prompt (I know I should have pushed a key to it but that’s immaterial) and it’d then hang before terminating the session.

OpenSSH has recently been trying to enforce a QoS level that the Pi Zero and Zero 2’s feeble wifi can’t satisfy leading to timeouts. The solution is to add the following line

IPQoS 0x00

to /etc/ssh/ssh_config and /etc/ssh/sshd_config.