most possible reason is sshd crash, but we cannot confirm this until we get access to device.
how to generate SSH host keys using various commands in shell mode
https://kb.juniper.net/InfoCenter/index?page=content&id=KB24078
most possible reason is sshd crash, but we cannot confirm this until we get access to device.
how to generate SSH host keys using various commands in shell mode
https://kb.juniper.net/InfoCenter/index?page=content&id=KB24078