diff --git a/src/modules/discovery/discovery.c b/src/modules/discovery/discovery.c
index 1b0170d..afefd07 100644
--- a/src/modules/discovery/discovery.c
+++ b/src/modules/discovery/discovery.c
@@ -204,13 +204,16 @@ static void *receive_thread_fn(void *arg) {
 
 		uint32_t addr = src.sin_addr.s_addr;
 		uint64_t ts   = now_ms();
-		int      is_new = 0;
+		int      is_new        = 0;
+		int      reannounce    = 0;
 		struct Discovery_Peer peer_copy;
 
 		pthread_mutex_lock(&d->peers_mutex);
 
 		int idx = find_peer(d, addr, tcp_port);
 		if (idx >= 0) {
+			/* detect restart: same addr+port but site_id changed */
+			if (d->peers[idx].info.site_id != site_id) { reannounce = 1; }
 			d->peers[idx].last_seen_ms        = ts;
 			d->peers[idx].info.site_id        = site_id;
 			d->peers[idx].info.tcp_port       = tcp_port;
@@ -233,9 +236,9 @@ static void *receive_thread_fn(void *arg) {
 
 		pthread_mutex_unlock(&d->peers_mutex);
 
-		if (is_new) {
-			/* announce ourselves immediately so the new peer learns about us
-			 * without waiting up to interval_ms */
+		if (is_new || reannounce) {
+			/* new peer, or peer restarted (site_id changed) — announce ourselves
+			 * immediately so it learns about us without waiting up to interval_ms */
 			pthread_mutex_lock(&d->announce_mutex);
 			pthread_cond_signal(&d->announce_cond);
 			pthread_mutex_unlock(&d->announce_mutex);