I’ve had some intermittent problems when for some reason despite DHCP being configured correctly, nodes will not PXE boot for MAAS discovery.
I’ve found a fix that works for me, it’s to restart the Twisted TFTP server by doing the following:
sudo service maas-pserv stop
sudo service maas-pserv start
It’s a strange one as connecting to the tftp server on the local machine works, but it just sits there waiting on the PXE. This seems to solve it.