diff --git a/peer/remotefsm.go b/peer/remotefsm.go
index 14d9261..9f6a442 100644
--- a/peer/remotefsm.go
+++ b/peer/remotefsm.go
@@ -212,6 +212,8 @@ func (r *remoteFSM) stateServer_onProbe(msg controlMsg[packetProbe]) {
 func (r *remoteFSM) stateServer_onPingTimer() {
 	conf := r.conf()
 	if time.Since(r.lastSeen) > timeoutInterval && conf.Up {
+		// Reset trace ID to ensure connection goes up on next SYN.
+		r.traceID = 0
 		conf.Up = false
 		r.updateConf(conf)
 		r.logf("Timeout.")