diff --git a/common/sniff/sniff.go b/common/sniff/sniff.go
index 8c7a0d3e..4d990092 100644
--- a/common/sniff/sniff.go
+++ b/common/sniff/sniff.go
@@ -24,12 +24,12 @@ func PeekStream(ctx context.Context, conn net.Conn, buffer *buf.Buffer, timeout
 	}
 	err := conn.SetReadDeadline(time.Now().Add(timeout))
 	if err != nil {
-		return nil, err
+		return nil, E.Cause(err, "set read deadline")
 	}
 	_, err = buffer.ReadOnceFrom(conn)
 	err = E.Errors(err, conn.SetReadDeadline(time.Time{}))
 	if err != nil {
-		return nil, err
+		return nil, E.Cause(err, "read payload")
 	}
 	var metadata *adapter.InboundContext
 	var errors []error
diff --git a/route/router.go b/route/router.go
index d46ca16c..5195367e 100644
--- a/route/router.go
+++ b/route/router.go
@@ -660,7 +660,7 @@ func (r *Router) RouteConnection(ctx context.Context, conn net.Conn, metadata ad
 	if metadata.InboundOptions.SniffEnabled {
 		buffer := buf.NewPacket()
 		buffer.FullReset()
-		sniffMetadata, _ := sniff.PeekStream(ctx, conn, buffer, time.Duration(metadata.InboundOptions.SniffTimeout), sniff.StreamDomainNameQuery, sniff.TLSClientHello, sniff.HTTPHost)
+		sniffMetadata, err := sniff.PeekStream(ctx, conn, buffer, time.Duration(metadata.InboundOptions.SniffTimeout), sniff.StreamDomainNameQuery, sniff.TLSClientHello, sniff.HTTPHost)
 		if sniffMetadata != nil {
 			metadata.Protocol = sniffMetadata.Protocol
 			metadata.Domain = sniffMetadata.Domain
@@ -675,6 +675,8 @@ func (r *Router) RouteConnection(ctx context.Context, conn net.Conn, metadata ad
 			} else {
 				r.logger.DebugContext(ctx, "sniffed protocol: ", metadata.Protocol)
 			}
+		} else if err != nil {
+			r.logger.TraceContext(ctx, "sniffed no protocol: ", err)
 		}
 		if !buffer.IsEmpty() {
 			conn = bufio.NewCachedConn(conn, buffer)