diff --git a/plugins/TrimeshReader/TrimeshReader.py b/plugins/TrimeshReader/TrimeshReader.py
index 7d1f182720..91f8423579 100644
--- a/plugins/TrimeshReader/TrimeshReader.py
+++ b/plugins/TrimeshReader/TrimeshReader.py
@@ -89,7 +89,7 @@ class TrimeshReader(MeshReader):
         # try to figure out the format, but for GLTF, it loads it as a binary file with flags "rb", and the json.load()
         # doesn't like it. For some reason, this seems to happen with 3.5.7, but not 3.7.1. Below is a workaround to
         # pass a file object that has been opened with "r" instead "rb" to load a GLTF file.
-        if file_name.endswith(".gltf"):
+        if file_name.lower().endswith(".gltf"):
             mesh_or_scene = trimesh.load(open(file_name, "r", encoding = "utf-8"), file_type = "gltf")
         else:
             mesh_or_scene = trimesh.load(file_name)
diff --git a/plugins/UM3NetworkPrinting/src/Models/Http/ClusterPrinterStatus.py b/plugins/UM3NetworkPrinting/src/Models/Http/ClusterPrinterStatus.py
index 2d2806050a..69daa1f08b 100644
--- a/plugins/UM3NetworkPrinting/src/Models/Http/ClusterPrinterStatus.py
+++ b/plugins/UM3NetworkPrinting/src/Models/Http/ClusterPrinterStatus.py
@@ -66,7 +66,11 @@ class ClusterPrinterStatus(BaseModel):
     ## Creates a new output model.
     #  \param controller - The controller of the model.
     def createOutputModel(self, controller: PrinterOutputController) -> PrinterOutputModel:
-        model = PrinterOutputModel(controller, len(self.configuration), firmware_version = self.firmware_version)
+        # FIXME
+        # Note that we're using '2' here as extruder count. We have hardcoded this for now to prevent issues where the
+        # amount of extruders coming back from the API is actually lower (which it can be if a printer was just added
+        # to a cluster). This should be fixed in the future, probably also on the cluster API side.
+        model = PrinterOutputModel(controller, 2, firmware_version = self.firmware_version)
         self.updateOutputModel(model)
         return model
 
@@ -80,6 +84,11 @@ class ClusterPrinterStatus(BaseModel):
         model.updateBuildplate(self.build_plate.type if self.build_plate else "glass")
         model.setCameraUrl(QUrl("http://{}:8080/?action=stream".format(self.ip_address)))
 
+        if not model.printerConfiguration:
+            # Prevent accessing printer configuration when not available.
+            # This sometimes happens when a printer was just added to a group and Cura is connected to that group.
+            return
+
         # Set the possible configurations based on whether a Material Station is present or not.
         if self.material_station and self.material_station.material_slots:
             self._updateAvailableConfigurations(model)
diff --git a/plugins/UM3NetworkPrinting/src/Network/LocalClusterOutputDeviceManager.py b/plugins/UM3NetworkPrinting/src/Network/LocalClusterOutputDeviceManager.py
index e55eb12fed..89fd71d03c 100644
--- a/plugins/UM3NetworkPrinting/src/Network/LocalClusterOutputDeviceManager.py
+++ b/plugins/UM3NetworkPrinting/src/Network/LocalClusterOutputDeviceManager.py
@@ -135,10 +135,13 @@ class LocalClusterOutputDeviceManager:
         ultimaker_machines = container_registry.findContainersMetadata(type="machine", manufacturer="Ultimaker B.V.")
         found_machine_type_identifiers = {}  # type: Dict[str, str]
         for machine in ultimaker_machines:
-            machine_bom_number = machine.get("firmware_update_info", {}).get("id", None)
             machine_type = machine.get("id", None)
-            if machine_bom_number and machine_type:
-                found_machine_type_identifiers[str(machine_bom_number)] = machine_type
+            machine_bom_numbers = machine.get("bom_numbers", [])
+            if machine_type and machine_bom_numbers:
+                for bom_number in machine_bom_numbers:
+                    # This produces a n:1 mapping of bom numbers to machine types
+                    # allowing the S5R1 and S5R2 hardware to use a single S5 definition.
+                    found_machine_type_identifiers[str(bom_number)] = machine_type
         return found_machine_type_identifiers
 
     ## Add a new device.
diff --git a/resources/definitions/ultimaker3.def.json b/resources/definitions/ultimaker3.def.json
index bd7e96448a..b34ff3bdba 100644
--- a/resources/definitions/ultimaker3.def.json
+++ b/resources/definitions/ultimaker3.def.json
@@ -33,7 +33,10 @@
                 "https://software.ultimaker.com/releases/firmware/9066/stable/um-update.swu.version"
             ],
             "update_url": "https://ultimaker.com/firmware"
-        }
+        },
+        "bom_numbers": [
+            9066
+        ]
     },
 
 
diff --git a/resources/definitions/ultimaker3_extended.def.json b/resources/definitions/ultimaker3_extended.def.json
index c0d099366d..ba9824896f 100644
--- a/resources/definitions/ultimaker3_extended.def.json
+++ b/resources/definitions/ultimaker3_extended.def.json
@@ -30,7 +30,10 @@
                 "https://software.ultimaker.com/releases/firmware/9066/stable/um-update.swu.version"
             ],
             "update_url": "https://ultimaker.com/firmware"
-        }
+        },
+        "bom_numbers": [
+            9511
+        ]
     },
 
     "overrides": {
diff --git a/resources/definitions/ultimaker_s3.def.json b/resources/definitions/ultimaker_s3.def.json
index 0fbf4acd77..f7f3a038fe 100644
--- a/resources/definitions/ultimaker_s3.def.json
+++ b/resources/definitions/ultimaker_s3.def.json
@@ -34,7 +34,10 @@
             "id": 213482,
             "check_urls": ["https://software.ultimaker.com/releases/firmware/213482/stable/um-update.swu.version"],
             "update_url": "https://ultimaker.com/firmware"
-        }
+        },
+        "bom_numbers": [
+            213482
+        ]
     },
 
     "overrides": {
diff --git a/resources/definitions/ultimaker_s5.def.json b/resources/definitions/ultimaker_s5.def.json
index 81b3a704ff..fef8c87c27 100644
--- a/resources/definitions/ultimaker_s5.def.json
+++ b/resources/definitions/ultimaker_s5.def.json
@@ -35,7 +35,10 @@
             "id": 9051,
             "check_urls": ["https://software.ultimaker.com/releases/firmware/9051/stable/um-update.swu.version"],
             "update_url": "https://ultimaker.com/firmware"
-        }
+        },
+        "bom_numbers": [
+            9051, 214475
+        ]
     },
 
     "overrides": {