Reboot VM during provisioning

Packer
1

Hello,

I am trying to reboot the VM during provisioning. I am installing a newer Kernel and want to reboot to be able to remove the old one, which cannot be removed while running.
I tried multiple ways but unfortunately none of them worked for me.
I am using the latest Debian Bullseye ISO to create our private cloud image, and up to the reboot everything works fine.

Hier is the relevant hcl template:

  provisioner "shell" {
    environment_vars = [
      "BUILD_NAME=${var.build_name}",
      "IMAGE_DATE=${var.datestamp}.${var.build_id}"
    ]
    execute_command   = "echo 'vagrant' | {{ .Vars }} sudo -S -E bash '{{ .Path }}'"
    pause_before      = "2s"
    expect_disconnect = "true"
    scripts           = [
      "provision_scripts/grub.sh",
      "provision_scripts/apt.sh",
      "provision_scripts/kernel.sh",
    ]
  }

  provisioner "shell" {
    environment_vars = [
      "BUILD_NAME=${var.build_name}",
      "IMAGE_DATE=${var.datestamp}.${var.build_id}"
    ]
    execute_command  = "echo 'vagrant' | {{ .Vars }} sudo -S -E bash '{{ .Path }}'"
    pause_before     = "60s"
    scripts          = [
      "provision_scripts/install.sh",
      "provision_scripts/configure.sh",
      "provision_scripts/setup.sh",
      "provision_scripts/cleanup.sh",
      "provision_scripts/zerodisk.sh"
    ]
  }

in kernel.sh :

...................
...................
...................
log "Reboot and use the new Kernel"
reboot
#sleep 60
exit 0

Unfortunately packer breaks after the reboot without running the first script in the second provisioner with a Timeout during SSH handshake. The VM is up and running and sshd is listening to port 22 within 20 seconds after the reboot.

Any idea how to handle reboots between provisioning scripts?

Thanks