diff --git a/src/wifi/model/wifi-default-protection-manager.cc b/src/wifi/model/wifi-default-protection-manager.cc
index cf5caafd8..3a05324c6 100644
--- a/src/wifi/model/wifi-default-protection-manager.cc
+++ b/src/wifi/model/wifi-default-protection-manager.cc
@@ -58,6 +58,30 @@ WifiDefaultProtectionManager::TryAddMpdu (Ptr<const WifiMacQueueItem> mpdu,
 {
   NS_LOG_FUNCTION (this << *mpdu << &txParams);
 
+  // TB PPDUs need no protection (the soliciting Trigger Frame can be protected
+  // by an MU-RTS). Until MU-RTS is implemented, we disable protection also for:
+  // - Trigger Frames
+  // - DL MU PPDUs containing more than one PSDU
+  if (txParams.m_txVector.IsUlMu ()
+      || mpdu->GetHeader ().IsTrigger ()
+      || (txParams.m_txVector.IsDlMu () && txParams.GetPsduInfoMap ().size () > 1))
+    {
+      if (txParams.m_protection)
+        {
+          NS_ASSERT (txParams.m_protection->method == WifiProtection::NONE);
+          return nullptr;
+        }
+      return std::unique_ptr<WifiProtection> (new WifiNoProtection);
+    }
+
+  // If we are adding a second PSDU to a DL MU PPDU, switch to no protection
+  // (until MU-RTS is implemented)
+  if (txParams.m_txVector.IsDlMu () && txParams.GetPsduInfoMap ().size () == 1
+      && txParams.GetPsduInfo (mpdu->GetHeader ().GetAddr1 ()) == nullptr)
+    {
+      return std::unique_ptr<WifiProtection> (new WifiNoProtection);
+    }
+
   // if the current protection method (if any) is already RTS/CTS or CTS-to-Self,
   // it will not change by adding an MPDU
   if (txParams.m_protection
@@ -100,6 +124,12 @@ WifiDefaultProtectionManager::TryAggregateMsdu (Ptr<const WifiMacQueueItem> msdu
 
   NS_ASSERT (txParams.m_protection->method == WifiProtection::NONE);
 
+  // No protection for TB PPDUs
+  if (txParams.m_txVector.IsUlMu ())
+    {
+      return nullptr;
+    }
+
   std::unique_ptr<WifiProtection> protection;
   protection = GetPsduProtection (msdu->GetHeader (), txParams.GetSizeIfAggregateMsdu (msdu).second,
                                   txParams.m_txVector);