diff --git a/Daemon.cpp b/Daemon.cpp
index ea98378b..3836bd96 100644
--- a/Daemon.cpp
+++ b/Daemon.cpp
@@ -72,6 +72,8 @@ namespace i2p
 			if (i2p::util::config::GetArg("-unreachable", 0))
 				i2p::context.SetUnreachable ();
 
+			i2p::context.SetSupportsV6 (i2p::util::config::GetArg("-v6", 0));
+			
 			LogPrint("CMD parameters:");
 			for (int i = 0; i < argc; ++i)
 				LogPrint(i, "  ", argv[i]);
diff --git a/RouterContext.cpp b/RouterContext.cpp
index 2560e6d4..8832e81e 100644
--- a/RouterContext.cpp
+++ b/RouterContext.cpp
@@ -78,7 +78,7 @@ namespace i2p
 		auto newAddress = boost::asio::ip::address::from_string (host);
 		for (auto& address : m_RouterInfo.GetAddresses ())
 		{
-			if (address.host != newAddress)
+			if (address.host != newAddress && address.IsCompatible (newAddress))
 			{	
 				address.host = newAddress;
 				updated = true;
@@ -130,7 +130,15 @@ namespace i2p
 		// update
 		UpdateRouterInfo ();
 	}
-	
+
+	void RouterContext::SetSupportsV6 (bool supportsV6)
+	{
+		if (supportsV6)
+			m_RouterInfo.EnableV6 ();
+		else
+			m_RouterInfo.DisableV6 ();
+	}	
+		
 	bool RouterContext::Load ()
 	{
 		std::ifstream fk (i2p::util::filesystem::GetFullPath (ROUTER_KEYS).c_str (), std::ifstream::binary | std::ofstream::in);
diff --git a/RouterContext.h b/RouterContext.h
index e10a4192..35f11e2d 100644
--- a/RouterContext.h
+++ b/RouterContext.h
@@ -32,7 +32,9 @@ namespace i2p
 			void SetUnreachable ();				
 			bool AcceptsTunnels () const { return m_AcceptsTunnels; };
 			void SetAcceptsTunnels (bool acceptsTunnels) { m_AcceptsTunnels = acceptsTunnels; };
-
+			bool SupportsV6 () const { return m_RouterInfo.IsV6 (); };
+			void SetSupportsV6 (bool supportsV6);
+			
 			// implements LocalDestination
 			const i2p::data::PrivateKeys& GetPrivateKeys () const { return m_Keys; };
 			const uint8_t * GetEncryptionPrivateKey () const { return m_Keys.GetPrivateKey (); };
diff --git a/RouterInfo.cpp b/RouterInfo.cpp
index c88ae02c..960db401 100644
--- a/RouterInfo.cpp
+++ b/RouterInfo.cpp
@@ -458,7 +458,7 @@ namespace data
 		addr.cost = 2;
 		addr.date = 0;
 		m_Addresses.push_back(addr);	
-		m_SupportedTransports |= eNTCPV4;
+		m_SupportedTransports |= addr.host.is_v6 () ? eNTCPV6 : eNTCPV4;
 	}	
 
 	void RouterInfo::AddSSUAddress (const char * host, int port, const uint8_t * key)
@@ -471,7 +471,7 @@ namespace data
 		addr.date = 0;
 		memcpy (addr.key, key, 32);
 		m_Addresses.push_back(addr);	
-		m_SupportedTransports |= eSSUV4;
+		m_SupportedTransports |= addr.host.is_v6 () ? eNTCPV6 : eSSUV4;
 		m_Caps |= eSSUTesting; 
 		m_Caps |= eSSUIntroducer; 
 	}	
@@ -560,6 +560,34 @@ namespace data
 			return m_SupportedTransports & (eSSUV4 | eSSUV6);
 	}
 
+	bool RouterInfo::IsV6 () const
+	{
+		return m_SupportedTransports & (eNTCPV6 | eSSUV6);
+	}
+
+	void RouterInfo::EnableV6 ()
+	{
+		if (!IsV6 ())
+			m_SupportedTransports |= eNTCPV6;
+	}
+		
+	void RouterInfo::DisableV6 ()
+	{		
+		if (IsV6 ())
+		{	
+			m_SupportedTransports &= ~eNTCPV6; 
+			for (size_t i = 0; i < m_Addresses.size (); i++)
+			{
+				if (m_Addresses[i].transportStyle == i2p::data::RouterInfo::eTransportNTCP &&
+					m_Addresses[i].host.is_v6 ())
+				{
+					m_Addresses.erase (m_Addresses.begin () + i);
+					break;
+				}
+			}	
+		}	
+	}
+		
 	bool RouterInfo::UsesIntroducer () const
 	{
 		return m_Caps & Caps::eUnreachable; // non-reachable
diff --git a/RouterInfo.h b/RouterInfo.h
index a4ccb159..d5d775b1 100644
--- a/RouterInfo.h
+++ b/RouterInfo.h
@@ -75,6 +75,12 @@ namespace data
 				// SSU only
 				Tag<32> key; // intro key for SSU
 				std::vector<Introducer> introducers;
+
+				bool IsCompatible (const boost::asio::ip::address& other) const 
+				{
+					return (host.is_v4 () && other.is_v4 ()) ||
+						(host.is_v6 () && other.is_v6 ());
+				}	
 			};
 			
 			RouterInfo (const std::string& fullPath);
@@ -102,6 +108,9 @@ namespace data
 			bool IsFloodfill () const;
 			bool IsNTCP (bool v4only = true) const;
 			bool IsSSU (bool v4only = true) const;
+			bool IsV6 () const;
+			void EnableV6 ();
+			void DisableV6 ();
 			bool IsCompatible (const RouterInfo& other) const { return m_SupportedTransports & other.m_SupportedTransports; };
 			bool UsesIntroducer () const;
 			bool IsIntroducer () const { return m_Caps & eSSUIntroducer; };
diff --git a/Transports.cpp b/Transports.cpp
index b3a01aee..cfe368e7 100644
--- a/Transports.cpp
+++ b/Transports.cpp
@@ -253,7 +253,7 @@ namespace transport
 				{	
 					// existing session not found. create new 
 					// try NTCP first if message size < 16K
-					auto address = r->GetNTCPAddress ();
+					auto address = r->GetNTCPAddress (!context.SupportsV6 ()); 
 					if (address && !r->UsesIntroducer () && !r->IsUnreachable () && msg->GetLength () < NTCP_MAX_MESSAGE_SIZE)
 					{	
 						auto s = new NTCPClient (m_Service, address->host, address->port, *r);