diff --git a/test/unittest/transport/SharedMemTests.cpp b/test/unittest/transport/SharedMemTests.cpp
index 8459305fbbd..6cdc2ff7dc4 100644
--- a/test/unittest/transport/SharedMemTests.cpp
+++ b/test/unittest/transport/SharedMemTests.cpp
@@ -34,6 +34,8 @@
 #include <MockReceiverResource.h>
 #include <SharedMemGlobalMock.hpp>
 
+#include "../logging/mock/MockConsumer.h"
+
 using namespace eprosima::fastrtps;
 using namespace eprosima::fastrtps::rtps;
 using namespace eprosima::fastdds;
@@ -1409,20 +1411,18 @@ TEST_F(SHMTransportTests, port_not_ok_listener_recover)
     thread_listener.join();
 }
 
+//! This test has been updated to avoid flakiness #20993
 TEST_F(SHMTransportTests, buffer_recover)
 {
     auto shared_mem_manager = SharedMemManager::create(domain_name);
-
     auto segment = shared_mem_manager->create_segment(3, 3);
 
     shared_mem_manager->remove_port(1);
     auto pub_sub1_write = shared_mem_manager->open_port(1, 8, 1000, SharedMemGlobal::Port::OpenMode::Write);
-
     shared_mem_manager->remove_port(2);
     auto pub_sub2_write = shared_mem_manager->open_port(2, 8, 1000, SharedMemGlobal::Port::OpenMode::Write);
 
     auto sub1_read = shared_mem_manager->open_port(1, 8, 1000, SharedMemGlobal::Port::OpenMode::ReadExclusive);
-
     auto sub2_read = shared_mem_manager->open_port(2, 8, 1000, SharedMemGlobal::Port::OpenMode::ReadExclusive);
 
     bool exit_listeners = false;
@@ -1461,10 +1461,8 @@ TEST_F(SHMTransportTests, buffer_recover)
 
                             if (buffer)
                             {
-                                {
-                                    std::lock_guard<SharedMemSegment::mutex> lock(received_mutex);
-                                    listener2_recv_count.fetch_add(1);
-                                }
+                                listener2_recv_count.fetch_add(1);
+                                //std::cout << "Listener2 received " << listener2_recv_count.load() << std::endl;
                                 std::this_thread::sleep_for(std::chrono::milliseconds(listener2_sleep_ms));
                                 buffer.reset();
                                 received_cv.notify_one();
@@ -1472,12 +1470,19 @@ TEST_F(SHMTransportTests, buffer_recover)
                         }
                     });
 
+    Log::ClearConsumers();
+    Log::Flush();
+    eprosima::fastdds::dds::MockConsumer* mock_consumer = new eprosima::fastdds::dds::MockConsumer("RTPS_TRANSPORT_SHM");
+    Log::RegisterConsumer(std::unique_ptr<eprosima::fastdds::dds::LogConsumer>(mock_consumer));
+    Log::SetVerbosity(Log::Warning);
+    Log::SetErrorStringFilter(std::regex("Buffer is being invalidated.*"));
+
     // Test 1 (without port overflow)
     uint32_t send_counter = 0u;
 
     bool is_port_ok = false;
 
-    while (listener1_recv_count.load() < 16u)
+    while (listener2_recv_count.load() < 32u)
     {
         {
             // The segment should never overflow
@@ -1506,14 +1511,20 @@ TEST_F(SHMTransportTests, buffer_recover)
         }
     }
 
-    // The slow listener is 4 times slower than the fast one
-    ASSERT_LT(listener1_recv_count.load() * 3, listener2_recv_count.load());
-    ASSERT_GT(listener1_recv_count.load(), listener2_recv_count.load() / 5);
+    // The ration between the listeners activity (sleep) should correspond to the amount of entries read plus lost
+    auto consumed_entries = mock_consumer->ConsumedEntries().size(); // buffer reset warnings: non-read samples
     std::cout << "Test1:"
               << " Listener1_recv_count " << listener1_recv_count.load()
               << " Listener2_recv_count " << listener2_recv_count.load()
+              << " Warning entries consumed: " << consumed_entries
               << std::endl;
-
+    //ASSERT_EQ((listener1_recv_count.load() * (listener1_sleep_ms/listener2_sleep_ms)),
+    //          (listener2_recv_count.load() + consumed_entries));
+    //ASSERT_EQ((listener1_recv_count.load()+consumed_entries), listener2_recv_count.load());
+    // The slow listener is 4 times slower than the fast one
+    EXPECT_LT(listener1_recv_count.load() * 3, listener2_recv_count.load());
+    EXPECT_GE(listener1_recv_count.load() * 4, listener2_recv_count.load());
+    ASSERT_EQ(1, 0);
     // Test 2 (with port overflow)
     listener2_sleep_ms = 0u;
     send_counter = 0u;
@@ -1580,6 +1591,9 @@ TEST_F(SHMTransportTests, buffer_recover)
 
     thread_listener1.join();
     thread_listener2.join();
+
+    Log::Reset();
+    Log::KillThread();
 }
 
 TEST_F(SHMTransportTests, remote_segments_free)