diff --git a/component/outbound/dialer/alive_dialer_set.go b/component/outbound/dialer/alive_dialer_set.go
index 14d3efe..320cd2c 100644
--- a/component/outbound/dialer/alive_dialer_set.go
+++ b/component/outbound/dialer/alive_dialer_set.go
@@ -111,16 +111,14 @@ func (a *AliveDialerSet) SetAlive(dialer *Dialer, alive bool) {
 		if index >= 0 {
 			// This dialer is already alive.
 		} else {
-			// Not alive -> alive.
-			defer a.aliveChangeCallback(true)
+			// Dialer: not alive -> alive.
 			a.dialerToIndex[dialer] = len(a.inorderedAliveDialerSet)
 			a.inorderedAliveDialerSet = append(a.inorderedAliveDialerSet, dialer)
 		}
 	} else {
 		index := a.dialerToIndex[dialer]
 		if index >= 0 {
-			// Alive -> not alive.
-			defer a.aliveChangeCallback(false)
+			// Dialer: alive -> not alive.
 			// Remove the dialer from inorderedAliveDialerSet.
 			if index >= len(a.inorderedAliveDialerSet) {
 				a.log.Panicf("index:%v >= len(a.inorderedAliveDialerSet):%v", index, len(a.inorderedAliveDialerSet))
@@ -158,16 +156,22 @@ func (a *AliveDialerSet) SetAlive(dialer *Dialer, alive bool) {
 		}
 		if a.minLatency.dialer != oldBestDialer {
 			if a.minLatency.dialer != nil {
+				re := "re-"
+				if oldBestDialer == nil {
+					defer a.aliveChangeCallback(true)
+					re = ""
+				}
 				a.log.WithFields(logrus.Fields{
 					string(a.selectionPolicy): a.minLatency.latency,
 					"group":                   a.dialerGroupName,
-					"l4proto":                 a.l4proto,
+					"network":                 string(a.l4proto) + string(a.ipversion),
 					"dialer":                  a.minLatency.dialer.Name(),
-				}).Infof("Group re-selects dialer")
+				}).Infof("Group %vselects dialer", re)
 			} else {
+				defer a.aliveChangeCallback(false)
 				a.log.WithFields(logrus.Fields{
 					"group":   a.dialerGroupName,
-					"l4proto": a.l4proto,
+					"network": string(a.l4proto) + string(a.ipversion),
 				}).Infof("Group has no dialer alive")
 			}
 		}
@@ -177,7 +181,7 @@ func (a *AliveDialerSet) SetAlive(dialer *Dialer, alive bool) {
 			a.minLatency.dialer = dialer
 			a.log.WithFields(logrus.Fields{
 				"group":   a.dialerGroupName,
-				"l4proto": a.l4proto,
+				"network": string(a.l4proto) + string(a.ipversion),
 				"dialer":  a.minLatency.dialer.Name(),
 			}).Infof("Group selects dialer")
 		}
diff --git a/component/outbound/dialer/connectivity_check.go b/component/outbound/dialer/connectivity_check.go
index 1e6d3f6..3c80a2e 100644
--- a/component/outbound/dialer/connectivity_check.go
+++ b/component/outbound/dialer/connectivity_check.go
@@ -261,6 +261,9 @@ func (d *Dialer) Check(timeout time.Duration,
 	} else {
 		// Append timeout if there is any error or unexpected status code.
 		if err != nil {
+			if strings.Contains(err.Error(), "network is unreachable") {
+				err = fmt.Errorf("network is unreachable")
+			}
 			d.Log.WithFields(logrus.Fields{
 				// Add a space to ensure alphabetical order is first.
 				"network": string(opts.L4proto) + string(opts.IpVersion),
diff --git a/component/outbound/dialer_group.go b/component/outbound/dialer_group.go
index a8e40bf..df6714e 100644
--- a/component/outbound/dialer_group.go
+++ b/component/outbound/dialer_group.go
@@ -125,7 +125,7 @@ func (g *DialerGroup) Select(l4proto consts.L4ProtoStr, ipversion consts.IpVersi
 		if d == nil {
 			// No alive dialer.
 			g.log.WithFields(logrus.Fields{
-				"l4proto": l4proto,
+				"network": string(l4proto) + string(ipversion),
 				"group":   g.Name,
 			}).Warnf("No alive dialer in DialerGroup, use \"block\".")
 			return g.block, nil
@@ -143,7 +143,7 @@ func (g *DialerGroup) Select(l4proto consts.L4ProtoStr, ipversion consts.IpVersi
 		if d == nil {
 			// No alive dialer.
 			g.log.WithFields(logrus.Fields{
-				"l4proto": l4proto,
+				"network": string(l4proto) + string(ipversion),
 				"group":   g.Name,
 			}).Warnf("No alive dialer in DialerGroup, use \"block\".")
 			return g.block, nil
diff --git a/control/connectivity.go b/control/connectivity.go
index effd67c..5bff827 100644
--- a/control/connectivity.go
+++ b/control/connectivity.go
@@ -6,16 +6,28 @@
 package control
 
 import (
+	"fmt"
 	"github.com/cilium/ebpf"
 	"github.com/sirupsen/logrus"
+	"golang.org/x/sys/unix"
+	"strconv"
 )
 
+func FormatL4Proto(l4proto uint8) string {
+	if l4proto == unix.IPPROTO_TCP {
+		return "tcp"
+	}
+	if l4proto == unix.IPPROTO_UDP {
+		return "udp"
+	}
+	return strconv.Itoa(int(l4proto))
+}
+
 func (c *ControlPlaneCore) OutboundAliveChangeCallback(outbound uint8) func(alive bool, l4proto uint8, ipversion uint8) {
 	return func(alive bool, l4proto uint8, ipversion uint8) {
 		c.log.WithFields(logrus.Fields{
 			"alive":       alive,
-			"l4proto":     l4proto,
-			"ipversion":   ipversion,
+			"network":     fmt.Sprintf("%v+%v", FormatL4Proto(l4proto), ipversion),
 			"outbound_id": outbound,
 		}).Tracef("outbound alive state changed")
 
diff --git a/control/tcp.go b/control/tcp.go
index 8fca50b..77ba399 100644
--- a/control/tcp.go
+++ b/control/tcp.go
@@ -58,12 +58,14 @@ func (c *ControlPlane) handleConn(lConn net.Conn) (err error) {
 	if outboundIndex < 0 || int(outboundIndex) >= len(c.outbounds) {
 		return fmt.Errorf("outbound id from bpf is out of range: %v not in [0, %v]", outboundIndex, len(c.outbounds)-1)
 	}
-	dialer, err := outbound.Select(consts.L4ProtoStr_TCP, consts.IpVersionFromAddr(dst.Addr()))
+	l4proto := consts.L4ProtoStr_TCP
+	ipversion := consts.IpVersionFromAddr(dst.Addr())
+	dialer, err := outbound.Select(l4proto, ipversion)
 	if err != nil {
 		return fmt.Errorf("failed to select dialer from group %v: %w", outbound.Name, err)
 	}
 	c.log.WithFields(logrus.Fields{
-		"l4proto":  "TCP",
+		"network":  string(l4proto) + string(ipversion),
 		"outbound": outbound.Name,
 		"dialer":   dialer.Name(),
 	}).Infof("%v <-> %v", RefineSourceToShow(src, dst.Addr()), RefineAddrPortToShow(dst))
diff --git a/control/udp.go b/control/udp.go
index a022475..cd756bc 100644
--- a/control/udp.go
+++ b/control/udp.go
@@ -207,10 +207,9 @@ getNew:
 	// If the udp endpoint has been not alive, remove it from pool and get a new one.
 	if !isNew && !ue.Dialer.MustGetAlive(l4proto, ipversion) {
 		c.log.WithFields(logrus.Fields{
-			"src":       src.String(),
-			"l4proto":   l4proto,
-			"ipversion": ipversion,
-			"dialer":    ue.Dialer.Name(),
+			"src":     src.String(),
+			"network": string(l4proto) + string(ipversion),
+			"dialer":  ue.Dialer.Name(),
 		}).Debugln("Old udp endpoint is not alive and removed")
 		_ = DefaultUdpEndpointPool.Remove(src, ue)
 		goto getNew
@@ -223,7 +222,7 @@ getNew:
 		if isDns && c.log.IsLevelEnabled(logrus.DebugLevel) && len(dnsMessage.Questions) > 0 {
 			q := dnsMessage.Questions[0]
 			c.log.WithFields(logrus.Fields{
-				"l4proto":  "UDP(DNS)",
+				"network":  string(l4proto) + string(ipversion) + "(DNS)",
 				"outbound": outbound.Name,
 				"dialer":   d.Name(),
 				"qname":    strings.ToLower(q.Name.String()),
@@ -234,7 +233,7 @@ getNew:
 		} else {
 			// TODO: Set-up ip to domain mapping and show domain if possible.
 			c.log.WithFields(logrus.Fields{
-				"l4proto":  "UDP",
+				"network":  string(l4proto) + string(ipversion),
 				"outbound": outbound.Name,
 				"dialer":   d.Name(),
 			}).Infof("%v <-> %v",