diff --git a/cli.go b/cli.go
index 7926170..a9edf9d 100644
--- a/cli.go
+++ b/cli.go
@@ -225,7 +225,7 @@ func (c *Config) setRedundantOptions() {
 	}
 }
 
-//nolint:forbidigo,maintidx,gocognit
+//nolint:forbidigo,maintidx,gocognit,gocyclo
 func configFromCLI() (config *Config, logger *Logger, err error) {
 	var (
 		interfaceName string
@@ -407,6 +407,8 @@ func configFromCLI() (config *Config, logger *Logger, err error) {
 
 	if config.RelayIPv6 == nil && config.RelayIPv4 == nil {
 		return config, logger, fmt.Errorf("no relay IP configured: %s and %s", errIPv4, errIPv6) //nolint:errorlint
+	} else if errIPv6 != nil && config.Verbose {
+		logger.Errorf("Warning: could not auto-detect relay IPv6 address: %v", err)
 	}
 
 	config.LocalIPv6, err = getLinkLocalIPv6Address(config.Interface)
diff --git a/dhcpv6.go b/dhcpv6.go
index 1240290..e9ab2b6 100644
--- a/dhcpv6.go
+++ b/dhcpv6.go
@@ -10,6 +10,8 @@ import (
 	"strings"
 	"time"
 
+	cryptoRand "crypto/rand"
+
 	"github.com/insomniacslk/dhcp/dhcpv6"
 	"github.com/insomniacslk/dhcp/dhcpv6/server6"
 	"github.com/insomniacslk/dhcp/iana"
@@ -42,14 +44,37 @@ type DHCPv6Handler struct {
 
 // NewDHCPv6Handler returns a DHCPv6Handler.
 func NewDHCPv6Handler(config *Config, logger *Logger) *DHCPv6Handler {
-	return &DHCPv6Handler{
+	handler := &DHCPv6Handler{
 		logger: logger,
 		config: config,
-		serverID: &dhcpv6.DUIDLL{
+	}
+
+	if config.Interface.HardwareAddr != nil {
+		handler.serverID = &dhcpv6.DUIDLL{
 			HWType:        iana.HWTypeEthernet,
 			LinkLayerAddr: config.Interface.HardwareAddr,
-		},
+		}
+	} else {
+		handler.serverID = &dhcpv6.DUIDUUID{
+			UUID: generateUUID(),
+		}
 	}
+
+	return handler
+}
+
+func generateUUID() (uuid [16]byte) {
+	_, err := cryptoRand.Read(uuid[:])
+	if err != nil {
+		panic(err)
+	}
+
+	// Set version to 4 (random)
+	uuid[6] = (uuid[6] & 0x0f) | 0x40 //nolint:mnd
+	// Set variant to RFC 4122
+	uuid[8] = (uuid[8] & 0x3f) | 0x80 //nolint:mnd
+
+	return uuid
 }
 
 // Handler implements a server6.Handler.
diff --git a/router_advertisement.go b/router_advertisement.go
index cc39aab..bb50652 100644
--- a/router_advertisement.go
+++ b/router_advertisement.go
@@ -133,12 +133,13 @@ func sendRouterAdvertisement(c *ndp.Conn, receiver netip.Addr, stateless bool, r
 
 		RouterSelectionPreference: ndp.High,
 		RouterLifetime:            routerLifetime,
-		Options: []ndp.Option{
-			&ndp.LinkLayerAddress{
-				Direction: ndp.Source,
-				Addr:      routerMAC,
-			},
-		},
+	}
+
+	if len(routerMAC) == 0 {
+		raMessage.Options = append(raMessage.Options, &ndp.LinkLayerAddress{
+			Direction: ndp.Source,
+			Addr:      routerMAC,
+		})
 	}
 
 	if dnsAddr != nil {