diff --git a/include/llarp/service/endpoint.hpp b/include/llarp/service/endpoint.hpp
index ea8253a94..9907180b8 100644
--- a/include/llarp/service/endpoint.hpp
+++ b/include/llarp/service/endpoint.hpp
@@ -161,6 +161,8 @@ namespace llarp
         IntroSet currentIntroSet;
         /// the current selected intro
         Introduction selectedIntro;
+        /// set to true if we are updating the remote introset right now
+        bool updatingIntroSet;
 
         /// update the current selected intro to be a new best introduction
         void
diff --git a/llarp/link/utp.cpp b/llarp/link/utp.cpp
index 1bc33f1e6..84ea5433d 100644
--- a/llarp/link/utp.cpp
+++ b/llarp/link/utp.cpp
@@ -31,6 +31,8 @@ namespace llarp
         FragmentOverheadSize + FragmentBodySize;
     typedef llarp::AlignedBuffer< FragmentBufferSize > FragmentBuffer;
 
+    constexpr size_t MaxSend = 64;
+
     typedef llarp::AlignedBuffer< MAX_LINK_MSG_SIZE > MessageBuffer;
 
     struct LinkLayer;
@@ -47,8 +49,8 @@ namespace llarp
       llarp_time_t lastActive;
       const static llarp_time_t sessionTimeout = 30 * 1000;
 
+      std::deque< utp_iovec > vecq;
       std::deque< FragmentBuffer > sendq;
-      size_t sendBufOffset;
 
       FragmentBuffer recvBuf;
       size_t recvBufOffset;
@@ -101,11 +103,41 @@ namespace llarp
       void
       PumpWrite()
       {
+        if(!sock)
+          return;
+        ssize_t expect = 0;
+        std::vector< utp_iovec > vecs;
+        for(const auto& vec : vecq)
+        {
+          expect += vec.iov_len;
+          vecs.push_back(vec);
+        }
+        if(expect)
+        {
+          ssize_t s = utp_writev(sock, vecs.data(), vecs.size());
+          llarp::LogDebug("utp_writev wrote=", s, " expect=", expect,
+                          " to=", remoteAddr);
+
+          while(s > vecq.front().iov_len)
+          {
+            s -= vecq.front().iov_len;
+            vecq.pop_front();
+            sendq.pop_front();
+          }
+          if(vecq.size())
+          {
+            auto& front = vecq.front();
+            front.iov_len -= s;
+            front.iov_base = ((byte_t*)front.iov_base) + s;
+          }
+        }
+
+        /*
         while(sendq.size() > 0 && !stalled)
         {
           ssize_t expect = FragmentBufferSize - sendBufOffset;
-          ssize_t s = write_ll(sendq.front().data() + sendBufOffset, expect);
-          if(s != expect)
+          ssize_t s      = write_ll(sendq.front().data() + sendBufOffset,
+        expect); if(s != expect)
           {
             llarp::LogDebug("stalled at offset=", sendBufOffset, " sz=", s,
                             " to ", remoteAddr);
@@ -118,6 +150,7 @@ namespace llarp
             sendq.pop_front();
           }
         }
+        */
       }
 
       ssize_t
@@ -540,14 +573,14 @@ namespace llarp
         return true;
       };
       gotLIM        = false;
-      sendBufOffset = 0;
       recvBufOffset = 0;
       TimedOut      = [&](llarp_time_t now) -> bool {
         return this->IsTimedOut(now) || this->state == eClose;
       };
       GetPubKey  = std::bind(&BaseSession::RemotePubKey, this);
       lastActive = llarp_time_now_ms();
-      Pump       = std::bind(&BaseSession::PumpWrite, this);
+      // Pump       = []() {};
+      Pump = std::bind(&BaseSession::PumpWrite, this);
       Tick = std::bind(&BaseSession::TickImpl, this, std::placeholders::_1);
       SendMessageBuffer = std::bind(&BaseSession::QueueWriteBuffers, this,
                                     std::placeholders::_1);
@@ -743,12 +776,7 @@ namespace llarp
         }
         else if(arg->state == UTP_STATE_WRITABLE)
         {
-          if(session->IsEstablished())
-          {
-            llarp::LogDebug("write resumed for ", session->remoteAddr);
-            session->stalled = false;
-            session->PumpWrite();
-          }
+          session->PumpWrite();
         }
         else if(arg->state == UTP_STATE_EOF)
         {
@@ -779,6 +807,10 @@ namespace llarp
     {
       sendq.emplace_back();
       auto& buf = sendq.back();
+      vecq.emplace_back();
+      auto& vec    = vecq.back();
+      vec.iov_base = buf.data();
+      vec.iov_len  = FragmentBufferSize;
       llarp::LogDebug("encrypt then hash ", sz, " bytes last=", isLastFragment);
       buf.Randomize();
       byte_t* nonce = buf.data() + FragmentHashSize;
diff --git a/llarp/service/endpoint.cpp b/llarp/service/endpoint.cpp
index 209522e03..4446b243e 100644
--- a/llarp/service/endpoint.cpp
+++ b/llarp/service/endpoint.cpp
@@ -720,8 +720,8 @@ namespace llarp
         auto itr = m_PendingServiceLookups.find(addr);
         if(itr != m_PendingServiceLookups.end())
         {
-          itr->second(addr, nullptr);
           m_PendingServiceLookups.erase(itr);
+          itr->second(addr, nullptr);
         }
         return false;
       }
@@ -778,6 +778,7 @@ namespace llarp
         , m_Parent(parent)
 
     {
+      updatingIntroSet = false;
       selectedIntro.Clear();
       ShiftIntroduction();
     }
@@ -795,6 +796,7 @@ namespace llarp
         currentIntroSet = *i;
         ShiftIntroduction();
       }
+      updatingIntroSet = false;
       return true;
     }
 
@@ -843,7 +845,7 @@ namespace llarp
       for(const auto& intro : currentIntroSet.I)
       {
         m_Parent->EnsureRouterIsKnown(selectedIntro.router);
-        if(intro.expiresAt > selectedIntro.expiresAt)
+        if(selectedIntro < intro)
         {
           selectedIntro = intro;
           shifted       = true;
@@ -1008,6 +1010,8 @@ namespace llarp
     void
     Endpoint::OutboundContext::UpdateIntroSet()
     {
+      if(updatingIntroSet)
+        return;
       auto addr = currentIntroSet.A.Addr();
       auto path = m_Parent->PickRandomEstablishedPath();
       if(path)
@@ -1018,8 +1022,7 @@ namespace llarp
                       std::placeholders::_1, std::placeholders::_2),
             addr, m_Parent->GenTXID());
 
-        if(!job->SendRequestViaPath(path, m_Parent->Router()))
-          llarp::LogError("send via path failed");
+        updatingIntroSet = job->SendRequestViaPath(path, m_Parent->Router());
       }
       else
       {
@@ -1032,10 +1035,9 @@ namespace llarp
     bool
     Endpoint::OutboundContext::Tick(llarp_time_t now)
     {
-      if(selectedIntro.expiresAt <= now
-         || selectedIntro.expiresAt - now < 30000)
+      if(selectedIntro.ExpiresSoon(now))
       {
-        UpdateIntroSet();
+        ShiftIntroduction();
       }
       m_Parent->EnsureRouterIsKnown(selectedIntro.router);
       // TODO: check for expiration of outbound context