diff --git a/README.md b/README.md
index 345f3f5..ef2fcce 100644
--- a/README.md
+++ b/README.md
@@ -32,6 +32,10 @@ Connection Server authority into a client.
 - The Protocol repository is the sole wire-contract authority; consumers pin
   an immutable release without a filesystem `replace`.
 
+The gateway requires an explicit `-advertise-address host:port`; it is the
+only endpoint placed in the Server registration and must be client-reachable.
+Apollo management and RTSP addresses remain private gateway-side inputs.
+
 ## Verification
 
 The baseline uses Go 1.26.5 and OpenSpec 1.5.0:
diff --git a/cmd/verse-gateway/main.go b/cmd/verse-gateway/main.go
index 0642f07..951f838 100644
--- a/cmd/verse-gateway/main.go
+++ b/cmd/verse-gateway/main.go
@@ -8,6 +8,7 @@ import (
 	"flag"
 	"fmt"
 	"log"
+	"net"
 	"os"
 	"os/signal"
 	"strings"
@@ -27,10 +28,11 @@ func main() {
 }
 
 func run() error {
-	var listen, controlPlane, certFile, keyFile, clientCAFile string
+	var listen, advertiseAddress, controlPlane, certFile, keyFile, clientCAFile string
 	var gatewayID, instanceIdentity, certificateIdentity, publicIdentity string
 	var providerManagement, providerRTSPAddress, providerRTSPURL, providerIdentity string
 	flag.StringVar(&listen, "listen", "0.0.0.0:443", "gateway QUIC listen address")
+	flag.StringVar(&advertiseAddress, "advertise-address", "", "client-visible gateway address host:port")
 	flag.StringVar(&controlPlane, "control-plane", "", "Connection Server HTTPS base URL")
 	flag.StringVar(&certFile, "cert", "", "gateway certificate PEM")
 	flag.StringVar(&keyFile, "key", "", "gateway private key PEM")
@@ -44,11 +46,14 @@ func run() error {
 	flag.StringVar(&providerRTSPURL, "provider-rtsp-url", "", "internal Apollo RTSP URL")
 	flag.StringVar(&providerIdentity, "provider-identity", "", "enrolled Apollo identity unique-id#fingerprint")
 	flag.Parse()
-	for name, value := range map[string]string{"control-plane": controlPlane, "cert": certFile, "key": keyFile, "client-ca": clientCAFile, "gateway-id": gatewayID, "instance-identity": instanceIdentity, "certificate-identity": certificateIdentity, "provider-management": providerManagement, "provider-rtsp-address": providerRTSPAddress, "provider-rtsp-url": providerRTSPURL, "provider-identity": providerIdentity} {
+	for name, value := range map[string]string{"control-plane": controlPlane, "advertise-address": advertiseAddress, "cert": certFile, "key": keyFile, "client-ca": clientCAFile, "gateway-id": gatewayID, "instance-identity": instanceIdentity, "certificate-identity": certificateIdentity, "provider-management": providerManagement, "provider-rtsp-address": providerRTSPAddress, "provider-rtsp-url": providerRTSPURL, "provider-identity": providerIdentity} {
 		if value == "" {
 			return fmt.Errorf("-%s is required", name)
 		}
 	}
+	if err := validateAdvertisedAddress(advertiseAddress); err != nil {
+		return err
+	}
 	expectedIdentity, err := parseProviderIdentity(providerIdentity)
 	if err != nil {
 		return err
@@ -66,7 +71,7 @@ func run() error {
 	if err != nil {
 		return err
 	}
-	registration := protocol.GatewayRegistration{Version: "1", GatewayID: gatewayID, InstanceIdentity: instanceIdentity, CertificateIdentity: certificateIdentity, PublicIdentity: publicIdentity, Address: server.Addr().String(), ProviderIdentity: providerIdentity, ProtocolMinVersion: 1, ProtocolMaxVersion: 1, ConnectionCapacity: 8, BandwidthCapacityKbps: 100000, Features: []string{"quic-tls13", "datagram.media", "apollo"}, Capabilities: capabilities}
+	registration := protocol.GatewayRegistration{Version: "1", GatewayID: gatewayID, InstanceIdentity: instanceIdentity, CertificateIdentity: certificateIdentity, PublicIdentity: publicIdentity, Address: advertiseAddress, ProviderIdentity: providerIdentity, ProtocolMinVersion: 1, ProtocolMaxVersion: 1, ConnectionCapacity: 8, BandwidthCapacityKbps: 100000, Features: []string{"quic-tls13", "datagram.media", "apollo"}, Capabilities: capabilities}
 	if _, err := controlPlaneClient.Register(context.Background(), registration); err != nil {
 		_ = server.Close()
 		return err
@@ -77,6 +82,20 @@ func run() error {
 	return server.Serve(ctx)
 }
 
+func validateAdvertisedAddress(address string) error {
+	host, port, err := net.SplitHostPort(address)
+	if err != nil || host == "" || port == "" {
+		return fmt.Errorf("-advertise-address must be a host:port address")
+	}
+	if parsed := net.ParseIP(host); parsed != nil && parsed.IsUnspecified() {
+		return fmt.Errorf("-advertise-address must not be an unspecified address")
+	}
+	if net.JoinHostPort(host, port) != address {
+		return fmt.Errorf("-advertise-address must use canonical host:port syntax")
+	}
+	return nil
+}
+
 func heartbeatLoop(ctx context.Context, client *gateway.ControlPlaneClient, server *gateway.Server, registration protocol.GatewayRegistration) {
 	ticker := time.NewTicker(2 * time.Second)
 	defer ticker.Stop()