diff --git a/deltachat-rpc-client/tests/test_webxdc_iroh.py b/deltachat-rpc-client/tests/test_webxdc_iroh.py
index 20f7ee453..0db83a039 100644
--- a/deltachat-rpc-client/tests/test_webxdc_iroh.py
+++ b/deltachat-rpc-client/tests/test_webxdc_iroh.py
@@ -25,7 +25,8 @@ def path_to_webxdc():
     return "../test-data/webxdc/chess.xdc"
 
 
-def test_basic_iroh_jsonrpc(acfactory, path_to_webxdc):
+def test_realtime_sequentially(acfactory, path_to_webxdc):
+    """Test two peers trying to establish connection sequentially."""
     ac1, ac2 = acfactory.get_online_accounts(2)
     ac1.create_chat(ac2)
     ac2.create_chat(ac1)
@@ -44,7 +45,7 @@ def test_basic_iroh_jsonrpc(acfactory, path_to_webxdc):
     snapshot = ac2_webxdc_msg.get_snapshot()
     assert snapshot.text == "play"
 
-    # send iroh announcements
+    # send iroh announcements sequentially
     log("sending ac1 -> ac2 realtime advertisement and additional message")
     ac1._rpc.send_webxdc_realtime_advertisement(ac1.id, ac1_webxdc_msg.id)
     acfactory.send_message(from_account=ac1, to_account=ac2, text="ping1")
@@ -70,5 +71,53 @@ def test_basic_iroh_jsonrpc(acfactory, path_to_webxdc):
         if event.kind == EventType.WEBXDC_REALTIME_DATA:
             assert event.data == [13, 15, 17]
             break
-        # else:
-        #    log(f"ignoring {event.kind}")
+
+
+def test_realtime_simultaneously(acfactory, path_to_webxdc):
+    """Test two peers trying to establish connection simultaneously."""
+    ac1, ac2 = acfactory.get_online_accounts(2)
+    ac1.create_chat(ac2)
+    ac2.create_chat(ac1)
+    acfactory.send_message(from_account=ac1, to_account=ac2, text="ping0")
+    snapshot = ac2.get_message_by_id(ac2.wait_for_incoming_msg_event().msg_id).get_snapshot()
+    assert snapshot.text == "ping0"
+
+    def log(msg):
+        print()
+        print("*" * 80 + "\n" + msg + "\n", file=sys.stderr)
+        print()
+
+    # share a webxdc app between ac1 and ac2
+    ac1_webxdc_msg = acfactory.send_message(from_account=ac1, to_account=ac2, text="play", file=path_to_webxdc)
+    ac2_webxdc_msg = ac2.get_message_by_id(ac2.wait_for_incoming_msg_event().msg_id)
+    snapshot = ac2_webxdc_msg.get_snapshot()
+    assert snapshot.text == "play"
+
+    # send iroh announcements simultaneously
+    log("sending ac1 -> ac2 realtime advertisement and additional message")
+    ac1._rpc.send_webxdc_realtime_advertisement(ac1.id, ac1_webxdc_msg.id)
+    acfactory.send_message(from_account=ac1, to_account=ac2, text="ping1")
+
+    log("sending ac2 -> ac1 realtime advertisement and additional message")
+    ac2._rpc.send_webxdc_realtime_advertisement(ac2.id, ac2_webxdc_msg.id)
+    acfactory.send_message(from_account=ac2, to_account=ac1, text="ping2")
+
+    # Ensure that advertisements have been received.
+
+    log("waiting for incoming message on ac2")
+    snapshot = ac2.get_message_by_id(ac2.wait_for_incoming_msg_event().msg_id).get_snapshot()
+    assert snapshot.text == "ping1"
+
+    log("waiting for incoming message on ac1")
+    snapshot = ac1.get_message_by_id(ac1.wait_for_incoming_msg_event().msg_id).get_snapshot()
+    assert snapshot.text == "ping2"
+
+    log("sending realtime data ac1 -> ac2")
+    ac1._rpc.send_webxdc_realtime_data(ac1.id, ac1_webxdc_msg.id, [13, 15, 17])
+
+    log("ac2: waiting for realtime data")
+    while 1:
+        event = ac2.wait_for_event()
+        if event.kind == EventType.WEBXDC_REALTIME_DATA:
+            assert event.data == [13, 15, 17]
+            break