diff --git a/gcs/src/components/navbar.jsx b/gcs/src/components/navbar.jsx
index 9e11e5011..a899b17aa 100644
--- a/gcs/src/components/navbar.jsx
+++ b/gcs/src/components/navbar.jsx
@@ -37,6 +37,7 @@ import { useDispatch, useSelector } from "react-redux"
 import {
   ConnectionType,
   emitConnectToDrone,
+  emitDisconnectFromDrone,
   emitGetComPorts,
   emitStartForwarding,
   emitStopForwarding,
@@ -169,6 +170,9 @@ export default function Navbar() {
       <Modal
         opened={openedModal}
         onClose={() => {
+          if (connecting) {
+            dispatch(emitDisconnectFromDrone())
+          }
           dispatch(setConnectionModal(false))
           dispatch(setConnecting(false))
         }}
@@ -297,12 +301,14 @@ export default function Navbar() {
               variant="filled"
               color={"red"}
               onClick={() => {
+                if (connecting) {
+                  dispatch(emitDisconnectFromDrone())
+                }
                 dispatch(setConnectionModal(false))
                 dispatch(setConnecting(false))
               }}
-              disabled={connecting}
             >
-              Close
+              {connecting ? "Cancel" : "Close"}
             </Button>
             <Button
               variant="filled"
diff --git a/gcs/src/redux/middleware/emitters.js b/gcs/src/redux/middleware/emitters.js
index 036d94c23..53e525d20 100644
--- a/gcs/src/redux/middleware/emitters.js
+++ b/gcs/src/redux/middleware/emitters.js
@@ -99,7 +99,17 @@ export function handleEmitters(socket, store, action) {
     },
     {
       emitter: emitDisconnectFromDrone,
-      callback: () => socket.socket.emit("disconnect_from_drone"),
+      callback: () => {
+        const storeState = store.getState()
+        const isConnecting = storeState.droneConnection.connecting
+
+        if (isConnecting) {
+          socket.socket.emit("cancel_connect_to_drone")
+          return
+        }
+
+        socket.socket.emit("disconnect_from_drone")
+      },
     },
     {
       emitter: emitConnectToDrone,
diff --git a/radio/app/controllers/paramsController.py b/radio/app/controllers/paramsController.py
index 12a2b1a7e..eb11642c6 100644
--- a/radio/app/controllers/paramsController.py
+++ b/radio/app/controllers/paramsController.py
@@ -77,10 +77,17 @@ def fetchAllParamsBlocking(
         self,
         timeout_secs: int = 120,
         progress_update_callback: Optional[Callable[[dict], None]] = None,
+        should_cancel_callback: Optional[Callable[[], bool]] = None,
     ) -> Response:
         """
         Fetches all parameters from the drone in a blocking manner.
         """
+        if should_cancel_callback and should_cancel_callback():
+            return {
+                "success": False,
+                "message": "Connection cancelled by user.",
+            }
+
         start_response = self._startFetchAll()
         if not start_response.get("success"):
             return start_response
@@ -89,6 +96,13 @@ def fetchAllParamsBlocking(
 
         try:
             while self.is_requesting_params:
+                if should_cancel_callback and should_cancel_callback():
+                    self.drone.logger.info("Parameter fetch cancelled by user")
+                    return {
+                        "success": False,
+                        "message": "Connection cancelled by user.",
+                    }
+
                 if time.time() > timeout:
                     self.drone.logger.error(
                         f"Fetching all parameters timed out after {timeout_secs} seconds"
diff --git a/radio/app/drone.py b/radio/app/drone.py
index d0effde5c..ceef355c9 100644
--- a/radio/app/drone.py
+++ b/radio/app/drone.py
@@ -85,6 +85,7 @@ def __init__(
         droneConnectStatusCb: Optional[Callable] = None,
         linkDebugStatsCb: Optional[Callable] = None,
         fetchingParameterCb: Optional[Callable] = None,
+        connectionCancelEvent: Optional[Event] = None,
     ) -> None:
         """
         The drone class interfaces with the UAS via MavLink.
@@ -95,6 +96,9 @@ def __init__(
             droneErrorCb (Optional[Callable], optional): Callback function for drone errors. Defaults to None.
             droneDisconnectCb (Optional[Callable], optional): Callback function for drone disconnection. Defaults to None.
             droneConnectStatusCb (Optional[Callable], optional): Callback function for drone connection providing an update as the drone connects. Defaults to None.
+            linkDebugStatsCb (Optional[Callable], optional): Callback function for link debug stats. Defaults to None.
+            fetchingParameterCb (Optional[Callable], optional): Callback function for when parameters are being fetched. Defaults to None.
+            connectionCancelEvent (Optional[Event], optional): Event to signal if the connection process should be cancelled. Defaults to None.
         """
         self.port = port
         self.baud = baud
@@ -104,6 +108,7 @@ def __init__(
         self.droneConnectStatusCb = droneConnectStatusCb
         self.linkDebugStatsCb = linkDebugStatsCb
         self.fetchingParameterCb = fetchingParameterCb
+        self.connection_cancel_event: Event = connectionCancelEvent or Event()
 
         self.connectionError: Optional[str] = None
         self._last_connect_progress: float = 0.0
@@ -148,12 +153,20 @@ def __init__(
                 self.connectionError = str(e)
             return
 
+        if self._isConnectionCancelRequested():
+            self._setCancelledConnectionErrorAndCloseMaster()
+            return
+
         try:
             initial_heartbeat = None
             heartbeat_timeout_secs = 5.0
             deadline = time.monotonic() + heartbeat_timeout_secs
 
             while True:
+                if self._isConnectionCancelRequested():
+                    self._setCancelledConnectionErrorAndCloseMaster()
+                    return
+
                 now = time.monotonic()
                 if now >= deadline:
                     break
@@ -249,6 +262,12 @@ def __init__(
 
         self.addMessageListener("STATUSTEXT", sendMessage)
 
+        if self._isConnectionCancelRequested():
+            self._setCancelledConnectionErrorAndCloseMaster()
+            self.is_active.clear()
+            self.stopAllThreads()
+            return
+
         self.getAutopilotVersion()
 
         if self.flight_sw_version is None:
@@ -289,6 +308,7 @@ def __init__(
         fetch_all_params_result = self.paramsController.fetchAllParamsBlocking(
             timeout_secs=120,
             progress_update_callback=self.sendParamFetchConnectionStatusUpdate,
+            should_cancel_callback=self._isConnectionCancelRequested,
         )
 
         if not fetch_all_params_result.get("success"):
@@ -311,6 +331,24 @@ def __init__(
             mavutil.mavlink.MAV_SEVERITY_INFO, "FGCS connected to aircraft"
         )
 
+    def _isConnectionCancelRequested(self) -> bool:
+        return self.connection_cancel_event.is_set()
+
+    def requestConnectionCancel(self) -> None:
+        self.connection_cancel_event.set()
+        if getattr(self, "paramsController", None) is not None:
+            self.paramsController.is_requesting_params = False
+
+    def _setCancelledConnectionErrorAndCloseMaster(self) -> None:
+        self.logger.info("Connection cancelled by user")
+        self.connectionError = "Connection cancelled by user."
+        if getattr(self, "master", None) is not None:
+            try:
+                self.master.close()
+            except Exception:
+                self.logger.exception("Failed to close connection during cancellation")
+            self.master = None
+
     def __getNextLogFilePath(self, line: str) -> str:
         return line.split("==NEXT_FILE==")[-1].split("==END==")[0]
 
@@ -931,8 +969,13 @@ def sendHeartbeatMessage(self) -> None:
             if sleep_time > 0:
                 time.sleep(sleep_time)
 
+            master = getattr(self, "master", None)
+            if master is None:
+                # Connection teardown can clear master while this thread is winding down.
+                break
+
             try:
-                self.master.mav.heartbeat_send(
+                master.mav.heartbeat_send(
                     mavutil.mavlink.MAV_TYPE_GCS,
                     mavutil.mavlink.MAV_AUTOPILOT_INVALID,
                     0,
@@ -1228,10 +1271,14 @@ def close(self) -> None:
 
         self.is_active.clear()
 
-        self.stopAllDataStreams()
+        if getattr(self, "master", None) is not None:
+            self.stopAllDataStreams()
         self.stopForwarding()
         self.stopAllThreads()
-        self.master.close()
+
+        if getattr(self, "master", None) is not None:
+            self.master.close()
+            self.master = None
 
         if len(self.log_file_names) == 0:
             self.logger.debug("No logs to save")
diff --git a/radio/app/droneStatus.py b/radio/app/droneStatus.py
index bc4ee4d2d..fa406ec39 100644
--- a/radio/app/droneStatus.py
+++ b/radio/app/droneStatus.py
@@ -3,11 +3,14 @@
 imports this and access it, it can update the values and every other file will also have the update due to passing by reference (probably).
 """
 
+from threading import Event, Lock
 from typing import List, Optional
 
-
 from app.drone import Drone
 
 correct_ports: List[str] = []
 drone: Optional[Drone] = None
 state: Optional[str] = None
+connection_state_lock: Lock = Lock()
+connection_in_progress: bool = False
+connect_cancel_event: Optional[Event] = None
diff --git a/radio/app/endpoints/comPorts.py b/radio/app/endpoints/comPorts.py
index 6d97b38cb..348f151e7 100644
--- a/radio/app/endpoints/comPorts.py
+++ b/radio/app/endpoints/comPorts.py
@@ -1,5 +1,6 @@
 import sys
 import time
+from threading import Event
 from typing import Optional
 
 from serial.tools import list_ports
@@ -11,9 +12,9 @@
 from app.utils import (
     droneConnectStatusCb,
     droneErrorCb,
+    fetchingParameterCb,
     getComPortNames,
     getFlightSwVersionString,
-    fetchingParameterCb,
 )
 
 
@@ -78,13 +79,6 @@ def connectToDrone(data: ConnectionDataType) -> None:
     Args:
         data: The message passed in from the client containing the form sent (select com port, baud rate)
     """
-    if droneStatus.drone:
-        droneStatus.drone.logger.warning(
-            "Attempting a connection to drone when connection is already established."
-        )
-        droneStatus.drone.close()
-        droneStatus.drone = None
-
     connectionType = data.get("connectionType")
 
     if connectionType not in ["serial", "network"]:
@@ -133,35 +127,77 @@ def connectToDrone(data: ConnectionDataType) -> None:
         droneStatus.drone = None
         return
 
-    drone = Drone(
-        port,
-        baud=baud,
-        forwarding_address=forwarding_address,
-        droneErrorCb=droneErrorCb,
-        droneDisconnectCb=disconnectFromDrone,
-        droneConnectStatusCb=droneConnectStatusCb,
-        linkDebugStatsCb=sendLinkDebugStats,
-        fetchingParameterCb=fetchingParameterCb,
-    )
-
-    if drone.connectionError is not None:
-        socketio.emit("connection_error", {"message": drone.connectionError})
-        droneStatus.drone = None
-        return
+    old_drone = None
+    with droneStatus.connection_state_lock:
+        if droneStatus.connection_in_progress:
+            socketio.emit(
+                "connection_error",
+                {"message": "A drone connection is already in progress."},
+            )
+            return
 
-    # Set droneStatus drone to local drone
-    droneStatus.drone = drone
+        if droneStatus.drone:
+            old_drone = droneStatus.drone
+            droneStatus.drone = None
 
-    # Sleeping for buffer time, if errors occur try changing back to 1 second
-    time.sleep(0.2)
-    logger.debug("Created drone instance")
-    socketio.emit(
-        "connected_to_drone",
-        {
-            "aircraft_type": drone.aircraft_type,
-            "flight_sw_version": getFlightSwVersionString(drone.flight_sw_version),
-        },
-    )
+        cancel_event = Event()
+        droneStatus.connect_cancel_event = cancel_event
+        droneStatus.connection_in_progress = True
+
+    if old_drone is not None:
+        old_drone.logger.warning(
+            "Attempting a connection to drone when connection is already established."
+        )
+        old_drone.close()
+
+    try:
+        drone = Drone(
+            port,
+            baud=baud,
+            forwarding_address=forwarding_address,
+            droneErrorCb=droneErrorCb,
+            droneDisconnectCb=disconnectFromDrone,
+            droneConnectStatusCb=droneConnectStatusCb,
+            linkDebugStatsCb=sendLinkDebugStats,
+            fetchingParameterCb=fetchingParameterCb,
+            connectionCancelEvent=cancel_event,
+        )
+
+        if drone.connectionError is not None:
+            socketio.emit("connection_error", {"message": drone.connectionError})
+            droneStatus.drone = None
+            return
+
+        # Set droneStatus drone to local drone
+        droneStatus.drone = drone
+
+        # Sleeping for buffer time, if errors occur try changing back to 1 second
+        time.sleep(0.2)
+        logger.debug("Created drone instance")
+        socketio.emit(
+            "connected_to_drone",
+            {
+                "aircraft_type": drone.aircraft_type,
+                "flight_sw_version": getFlightSwVersionString(drone.flight_sw_version),
+            },
+        )
+    finally:
+        with droneStatus.connection_state_lock:
+            droneStatus.connection_in_progress = False
+            droneStatus.connect_cancel_event = None
+
+
+@socketio.on("cancel_connect_to_drone")
+def cancelConnectToDrone() -> None:
+    """Cancel an in-progress drone connection attempt."""
+    with droneStatus.connection_state_lock:
+        if droneStatus.connection_in_progress and droneStatus.connect_cancel_event:
+            logger.info("Connection cancel requested by user")
+            droneStatus.connect_cancel_event.set()
+        else:
+            logger.debug(
+                "Connection cancel requested, but no connection is in progress"
+            )
 
 
 @socketio.on("disconnect_from_drone")
@@ -169,9 +205,22 @@ def disconnectFromDrone() -> None:
     """
     Disconnect from drone and reset all global variables, send a message to client disconnecting as well
     """
-    if droneStatus.drone:
-        droneStatus.drone.close()
-        droneStatus.drone = None
+    with droneStatus.connection_state_lock:
+        if droneStatus.drone:
+            drone = droneStatus.drone
+            droneStatus.drone = None
+        else:
+            drone = None
+
+        if (
+            drone is None
+            and droneStatus.connection_in_progress
+            and droneStatus.connect_cancel_event
+        ):
+            droneStatus.connect_cancel_event.set()
+
+    if drone is not None:
+        drone.close()
 
     droneStatus.state = None
     socketio.emit("disconnected_from_drone")
diff --git a/radio/tests/test_ParamsController.py b/radio/tests/test_ParamsController.py
index a14bbacc2..cc29ef8bb 100644
--- a/radio/tests/test_ParamsController.py
+++ b/radio/tests/test_ParamsController.py
@@ -92,3 +92,15 @@ def test_fetchAllParamsBlocking_success_sorts_and_updates_progress(droneStatus)
         assert controller.total_number_of_params == 0
     finally:
         controller.params = old_params
+
+
+def test_fetchAllParamsBlocking_cancelled_before_start(droneStatus) -> None:
+    controller = droneStatus.drone.paramsController
+
+    result = controller.fetchAllParamsBlocking(
+        timeout_secs=120,
+        should_cancel_callback=lambda: True,
+    )
+
+    assert result["success"] is False
+    assert result["message"] == "Connection cancelled by user."
diff --git a/radio/tests/test_connections.py b/radio/tests/test_connections.py
index c9ba46252..8f2c2fe0c 100644
--- a/radio/tests/test_connections.py
+++ b/radio/tests/test_connections.py
@@ -1,3 +1,5 @@
+from threading import Event
+
 import pytest
 from flask_socketio.test_client import SocketIOTestClient
 
@@ -171,6 +173,52 @@ def test_stopForwarding_notForwarding(socketio_client: SocketIOTestClient, drone
     }
 
 
+def test_connect_while_connection_in_progress_is_rejected(
+    socketio_client: SocketIOTestClient, droneStatus
+):
+    old_in_progress = droneStatus.connection_in_progress
+    old_cancel_event = droneStatus.connect_cancel_event
+
+    try:
+        droneStatus.connection_in_progress = True
+        socketio_client.emit(
+            "connect_to_drone",
+            {
+                "port": "tcp:127.0.0.1:5760",
+                "baud": 115200,
+                "connectionType": "network",
+                "forwardingAddress": None,
+            },
+        )
+
+        socketio_result = socketio_client.get_received()
+        assert socketio_result[0]["name"] == "connection_error"
+        assert socketio_result[0]["args"][0] == {
+            "message": "A drone connection is already in progress."
+        }
+    finally:
+        droneStatus.connection_in_progress = old_in_progress
+        droneStatus.connect_cancel_event = old_cancel_event
+
+
+def test_cancel_connect_to_drone_signals_cancel_event(
+    socketio_client: SocketIOTestClient, droneStatus
+):
+    old_in_progress = droneStatus.connection_in_progress
+    old_cancel_event = droneStatus.connect_cancel_event
+
+    try:
+        droneStatus.connection_in_progress = True
+        droneStatus.connect_cancel_event = Event()
+
+        socketio_client.emit("cancel_connect_to_drone")
+
+        assert droneStatus.connect_cancel_event.is_set() is True
+    finally:
+        droneStatus.connection_in_progress = old_in_progress
+        droneStatus.connect_cancel_event = old_cancel_event
+
+
 # Has to be the final test otherwise the socket disconnects
 def test_disconnect(socketio_client: SocketIOTestClient, droneStatus):
     """Test disconnecting from socket"""