diff --git a/quantnet_controller/common/constants.py b/quantnet_controller/common/constants.py
index 3f7487e..10f13c7 100644
--- a/quantnet_controller/common/constants.py
+++ b/quantnet_controller/common/constants.py
@@ -10,7 +10,7 @@ class Constants:
     DEFAULT_TEST_DB_NAME = "quantnet_test"
     DEFAULT_TEST_DB_URI = f"mongodb://localhost:27017/{DEFAULT_TEST_DB_NAME}"
     SLOTSIZE = timedelta(milliseconds=100)
-    MAX_TIMESLOTS = 500
+    MAX_TIMESLOTS = 1000
     NODE_HEARTBEAT_TIMEOUT = 60  # seconds
     PLUGIN_PATH = os.path.join(os.path.dirname(quantnet_controller.__file__), "plugins")
     DEFAULT_EXP_DEFS = os.path.join(os.path.dirname(quantnet_controller.__file__),
diff --git a/quantnet_controller/common/request_translator.py b/quantnet_controller/common/request_translator.py
index 488d3b6..24e3ae8 100644
--- a/quantnet_controller/common/request_translator.py
+++ b/quantnet_controller/common/request_translator.py
@@ -365,7 +365,15 @@ def find_common_slot(self, agent_ids, availabilities, exp_def):
         logger.info(f"Finding common timeslots from agents {agent_ids}")
         slots = {}
 
-        slot_mask = bitarray(max([get_timeslot_mask(i.sequences) for i in exp_def.agent_sequences]))
+        # Build the search pattern as the longest per-agent sequence, each capped to
+        # MAX_TIMESLOTS.  get_timeslot_mask() can return millions of slots for idle-wait
+        # agents (e.g. LBNL-C waiting for the whole experiment), which would exceed
+        # common_bit's length and make bitarray.find() return -1.
+        max_needed = max(
+            min(len(get_timeslot_mask(i.sequences)), Constants.MAX_TIMESLOTS)
+            for i in exp_def.agent_sequences
+        )
+        slot_mask = bitarray("1" * max_needed)
 
         common_bit = bitarray("1" * Constants.MAX_TIMESLOTS)
         for agent_id in agent_ids:
@@ -373,9 +381,15 @@ def find_common_slot(self, agent_ids, availabilities, exp_def):
 
         start_index = (common_bit).find(slot_mask)
 
+        if start_index == -1:
+            raise Exception(
+                f"No common free timeslot found across agents {agent_ids} "
+                f"for experiment requiring {len(slot_mask)} slots"
+            )
+
         for i in range(len(exp_def.agent_sequences)):
             agent_sequence = exp_def.agent_sequences[i]
-            seq_length = len(get_timeslot_mask(agent_sequence.sequences))
+            seq_length = min(len(get_timeslot_mask(agent_sequence.sequences)), Constants.MAX_TIMESLOTS)
             slot = list(range(start_index, start_index + seq_length))
             slots[agent_ids[i]] = slot
         return slots
@@ -441,13 +455,16 @@ async def translate_request(self, exp_id, exp, exp_params, agent_ids, handle_res
 
                 for sequence in agent_sequence.sequences:
                     timeslot = get_num_timeslot(sequence)
+                    assigned = timeslot_mask[:timeslot]
+                    timeslot_mask = timeslot_mask[timeslot:]
+                    if not assigned:
+                        continue
                     allocation = {
                         "expName": sequence.name,
                         "className": sequence.class_name,
                         "parameters": rpc_exp_params,
-                        "timeSlot": timeslot_mask[:timeslot],
+                        "timeSlot": assigned,
                     }
-                    timeslot_mask = timeslot_mask[timeslot:]
                     allocations.append(allocation)
                     logger.info(
                         f"Submitting sequences {sequence.name} to {agent_id} with slot {allocation['timeSlot']}"
@@ -501,7 +518,7 @@ async def translate_request(self, exp_id, exp, exp_params, agent_ids, handle_res
                 handle_result("error", str(e))
             return Code.FAILED
 
-    async def submit(self, agent_id, param, timeout=5.0):
+    async def submit(self, agent_id, param, timeout=30.0):
         """
         Submit a task to the specified agent.
 
diff --git a/regression_tests/conf/mosquitto.conf b/regression_tests/conf/mosquitto.conf
index 5105dd6..93a2ae5 100644
--- a/regression_tests/conf/mosquitto.conf
+++ b/regression_tests/conf/mosquitto.conf
@@ -10,3 +10,7 @@ allow_anonymous true
 
 connection_messages true
 log_timestamp true
+
+## Allow large MQTT packets (e.g. DQC requests with many commands)
+## Default is 2000000 bytes; 268435455 = MQTT protocol maximum (~256MB)
+max_packet_size 268435455