error message:

  Sub-process /usr/bin/sqv returned an error code (1), error message is: Missing key 827C8569F2518CC677FECA1AED65462EC8D5E4C5, which is needed to verify signature.

Some genius changed the key…

sudo curl -fsSL https://archive.kali.org/archive-key.asc | gpg --dearmor -o /etc/apt/trusted.gpg.d/kali.gpg

Once the node didn't start and was complaining /dev/sda1 had errors. At boot: press “e” to edit Grub's line starting with linux and remove quiet splash to put single fsck…. like:

linux /boot/vmlinuz-<version> root=UUID=<your-uuid> ro single fsck.mode=force fsck.repair=yes

And voilà !

Ethernet card switches off after a long period of inactivity?

ethtool -s <interface_name> wol d

Make it permanent:

 vi /etc/udev/rules.d/70-disable-ethernet-power-management.rules

ACTION=="add", SUBSYSTEM=="net", KERNEL=="eth*", RUN+="/usr/sbin/ethtool -s %k wol d"
ACTION=="add", SUBSYSTEM=="net", KERNEL=="enp*", RUN+="/usr/sbin/ethtool -s %k wol d"

udevadm control --reload-rules