diff --git a/p2p/nat/natpmp.go b/p2p/nat/natpmp.go
index 4a9644ac1a..ee07eb4ff6 100644
--- a/p2p/nat/natpmp.go
+++ b/p2p/nat/natpmp.go
@@ -49,6 +49,9 @@ func (n *pmp) AddMapping(protocol string, extport, intport int, name string, lif
 	if lifetime <= 0 {
 		return 0, errors.New("lifetime must not be <= 0")
 	}
+	if extport == 0 {
+		extport = intport
+	}
 	// Note order of port arguments is switched between our
 	// AddMapping and the client's AddPortMapping.
 	res, err := n.c.AddPortMapping(strings.ToLower(protocol), intport, extport, int(lifetime/time.Second))
diff --git a/p2p/nat/natupnp.go b/p2p/nat/natupnp.go
index 1014dc69d2..ed00b8eeb6 100644
--- a/p2p/nat/natupnp.go
+++ b/p2p/nat/natupnp.go
@@ -86,15 +86,15 @@ func (n *upnp) AddMapping(protocol string, extport, intport int, desc string, li
 	}
 	protocol = strings.ToUpper(protocol)
 	lifetimeS := uint32(lifetime / time.Second)
-	n.DeleteMapping(protocol, extport, intport)
 
-	err = n.withRateLimit(func() error {
-		return n.client.AddPortMapping("", uint16(extport), protocol, uint16(intport), ip.String(), true, desc, lifetimeS)
-	})
-	if err == nil {
-		return uint16(extport), nil
+	if extport == 0 {
+		extport = intport
+	} else {
+		// Only delete port mapping if the external port was already used by geth.
+		n.DeleteMapping(protocol, extport, intport)
 	}
-	// Try addAnyPortMapping if mapping specified port didn't work.
+
+	// Try to add port mapping, preferring the specified external port.
 	err = n.withRateLimit(func() error {
 		p, err := n.addAnyPortMapping(protocol, extport, intport, ip, desc, lifetimeS)
 		if err == nil {
@@ -105,18 +105,28 @@ func (n *upnp) AddMapping(protocol string, extport, intport int, desc string, li
 	return uint16(extport), err
 }
 
+// addAnyPortMapping tries to add a port mapping with the specified external port.
+// If the external port is already in use, it will try to assign another port.
 func (n *upnp) addAnyPortMapping(protocol string, extport, intport int, ip net.IP, desc string, lifetimeS uint32) (uint16, error) {
 	if client, ok := n.client.(*internetgateway2.WANIPConnection2); ok {
 		return client.AddAnyPortMapping("", uint16(extport), protocol, uint16(intport), ip.String(), true, desc, lifetimeS)
 	}
-	// It will retry with a random port number if the client does
-	// not support AddAnyPortMapping.
-	extport = n.randomPort()
+	// For IGDv1 and v1 services we should first try to add with extport.
 	err := n.client.AddPortMapping("", uint16(extport), protocol, uint16(intport), ip.String(), true, desc, lifetimeS)
-	if err != nil {
-		return 0, err
+	if err == nil {
+		return uint16(extport), nil
 	}
-	return uint16(extport), nil
+
+	// If above fails, we retry with a random port.
+	// We retry several times because of possible port conflicts.
+	for i := 0; i < 3; i++ {
+		extport = n.randomPort()
+		err := n.client.AddPortMapping("", uint16(extport), protocol, uint16(intport), ip.String(), true, desc, lifetimeS)
+		if err == nil {
+			return uint16(extport), nil
+		}
+	}
+	return 0, err
 }
 
 func (n *upnp) randomPort() int {
diff --git a/p2p/server_nat.go b/p2p/server_nat.go
index 933993bc1f..5830f950e1 100644
--- a/p2p/server_nat.go
+++ b/p2p/server_nat.go
@@ -150,14 +150,9 @@ func (srv *Server) portMappingLoop() {
 					continue
 				}
 
-				external := m.port
-				if m.extPort != 0 {
-					external = m.extPort
-				}
-				log := newLogger(m.protocol, external, m.port)
-
+				log := newLogger(m.protocol, m.extPort, m.port)
 				log.Trace("Attempting port mapping")
-				p, err := srv.NAT.AddMapping(m.protocol, external, m.port, m.name, portMapDuration)
+				p, err := srv.NAT.AddMapping(m.protocol, m.extPort, m.port, m.name, portMapDuration)
 				if err != nil {
 					log.Debug("Couldn't add port mapping", "err", err)
 					m.extPort = 0
@@ -167,8 +162,8 @@ func (srv *Server) portMappingLoop() {
 				// It was mapped!
 				m.extPort = int(p)
 				m.nextTime = srv.clock.Now().Add(portMapRefreshInterval)
-				if external != m.extPort {
-					log = newLogger(m.protocol, m.extPort, m.port)
+				log = newLogger(m.protocol, m.extPort, m.port)
+				if m.port != m.extPort {
 					log.Info("NAT mapped alternative port")
 				} else {
 					log.Info("NAT mapped port")