diff --git a/src/uds/services/PhysicalMachines/deployment_multi.py b/src/uds/services/PhysicalMachines/deployment_multi.py
index 9397b9c18..6fb5298a8 100644
--- a/src/uds/services/PhysicalMachines/deployment_multi.py
+++ b/src/uds/services/PhysicalMachines/deployment_multi.py
@@ -94,6 +94,9 @@ def get_unique_id(self) -> str:
 
     @typing.override
     def set_ready(self) -> types.states.TaskState:
+        # User-services migrated from v3.6 may carry an empty _mac, so refresh from
+        # the Server model before waking up or WOL would be sent to nothing.
+        self.update_ip()
         self.service().wakeup(self._ip, self._mac)
         return types.states.TaskState.FINISHED
 
diff --git a/src/uds/services/PhysicalMachines/provider.py b/src/uds/services/PhysicalMachines/provider.py
index b682d3103..9e33d36c4 100644
--- a/src/uds/services/PhysicalMachines/provider.py
+++ b/src/uds/services/PhysicalMachines/provider.py
@@ -36,7 +36,7 @@
 
 from django.utils.translation import gettext_noop as _
 
-from uds.core import exceptions, services, types
+from uds.core import consts, exceptions, services, types
 from uds.core.ui.user_interface import gui
 from uds.core.util import net, resolver
 
@@ -119,7 +119,7 @@ def wake_on_lan_endpoint(self, host: str, mac: str) -> str:
         Returns:
             str: URL of WOL server or empty ('') if no server for the ip is found
         """
-        if not self.config.value or not host or not mac:
+        if not self.config.value or not host or not mac or mac == consts.NULL_MAC:
             return ''
 
         # If host is a hostname, try to resolve it