Comment 9 for bug 1910552

"Are you saying that cloud-init is attempting to read metadata from MAAS, but then MAAS accepts the request but never sends a response?"

Yes. We also observed that if the packets are DROPed between the node and MAAS, then the boot process will be stuck as well.
REJECTing the packets allows the connection to be refused so the boot sequence immediately moves on.
(this happened to us on a node whose MAAS had been decommissioned, and corresponding firewall rules removed. Adding a rule to REJECT the packets had unblocked the boot sequence).

I could reproduce in a local test environment, DROPing packets along the way. I attached the logs. (The logs should show that after a few minutes, the node succeeds contacting MAAS. That's because I removed the rule at that point.).