diff --git a/internal/config/config.go b/internal/config/config.go
index b0e20717e..fbfe95b96 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -26,6 +26,7 @@ import (
 	"reflect"
 	"sort"
 	"strconv"
+	"strings"
 
 	"github.com/calmh/logger"
 	"github.com/syncthing/protocol"
@@ -35,7 +36,7 @@ import (
 
 var l = logger.DefaultLogger
 
-const CurrentVersion = 7
+const CurrentVersion = 8
 
 type Configuration struct {
 	Version        int                   `xml:"version,attr"`
@@ -162,7 +163,7 @@ type FolderDeviceConfiguration struct {
 
 type OptionsConfiguration struct {
 	ListenAddress           []string `xml:"listenAddress" default:"0.0.0.0:22000"`
-	GlobalAnnServers        []string `xml:"globalAnnounceServer" default:"udp4://announce.syncthing.net:22026"`
+	GlobalAnnServers        []string `xml:"globalAnnounceServer" default:"udp4://announce.syncthing.net:22026, udp6://announce-v6.syncthing.net:22026"`
 	GlobalAnnEnabled        bool     `xml:"globalAnnounceEnabled" default:"true"`
 	LocalAnnEnabled         bool     `xml:"localAnnounceEnabled" default:"true"`
 	LocalAnnPort            int      `xml:"localAnnouncePort" default:"21025"`
@@ -296,35 +297,28 @@ func (cfg *Configuration) prepare(myID protocol.DeviceID) {
 	cfg.Options.Deprecated_URDeclined = false
 	cfg.Options.Deprecated_UREnabled = false
 
-	// Upgrade to v1 configuration if appropriate
+	// Upgrade configuration versions as appropriate
 	if cfg.Version == 1 {
 		convertV1V2(cfg)
 	}
-
-	// Upgrade to v3 configuration if appropriate
 	if cfg.Version == 2 {
 		convertV2V3(cfg)
 	}
-
-	// Upgrade to v4 configuration if appropriate
 	if cfg.Version == 3 {
 		convertV3V4(cfg)
 	}
-
-	// Upgrade to v5 configuration if appropriate
 	if cfg.Version == 4 {
 		convertV4V5(cfg)
 	}
-
-	// Upgrade to v6 configuration if appropriate
 	if cfg.Version == 5 {
 		convertV5V6(cfg)
 	}
-
-	// Upgrade to v7 configuration if appropriate
 	if cfg.Version == 6 {
 		convertV6V7(cfg)
 	}
+	if cfg.Version == 7 {
+		convertV7V8(cfg)
+	}
 
 	// Hash old cleartext passwords
 	if len(cfg.GUI.Password) > 0 && cfg.GUI.Password[0] != '$' {
@@ -416,6 +410,15 @@ func ChangeRequiresRestart(from, to Configuration) bool {
 	return false
 }
 
+func convertV7V8(cfg *Configuration) {
+	// Add IPv6 announce server
+	if len(cfg.Options.GlobalAnnServers) == 1 && cfg.Options.GlobalAnnServers[0] == "udp4://announce.syncthing.net:22026" {
+		cfg.Options.GlobalAnnServers = append(cfg.Options.GlobalAnnServers, "udp6://announce-v6.syncthing.net:22026")
+	}
+
+	cfg.Version = 8
+}
+
 func convertV6V7(cfg *Configuration) {
 	// Migrate announce server addresses to the new URL based format
 	for i := range cfg.Options.GlobalAnnServers {
@@ -594,8 +597,16 @@ func fillNilSlices(data interface{}) error {
 			switch f.Interface().(type) {
 			case []string:
 				if f.IsNil() {
-					rv := reflect.MakeSlice(reflect.TypeOf([]string{}), 1, 1)
-					rv.Index(0).SetString(v)
+					// Treat the default as a comma separated slice
+					vs := strings.Split(v, ",")
+					for i := range vs {
+						vs[i] = strings.TrimSpace(vs[i])
+					}
+
+					rv := reflect.MakeSlice(reflect.TypeOf([]string{}), len(vs), len(vs))
+					for i, v := range vs {
+						rv.Index(i).SetString(v)
+					}
 					f.Set(rv)
 				}
 			}
@@ -615,6 +626,8 @@ func uniqueStrings(ss []string) []string {
 		us = append(us, k)
 	}
 
+	sort.Strings(us)
+
 	return us
 }
 
diff --git a/internal/config/config_test.go b/internal/config/config_test.go
index 8ed96c7e8..85b03a8e9 100644
--- a/internal/config/config_test.go
+++ b/internal/config/config_test.go
@@ -37,7 +37,7 @@ func init() {
 func TestDefaultValues(t *testing.T) {
 	expected := OptionsConfiguration{
 		ListenAddress:           []string{"0.0.0.0:22000"},
-		GlobalAnnServers:        []string{"udp4://announce.syncthing.net:22026"},
+		GlobalAnnServers:        []string{"udp4://announce.syncthing.net:22026", "udp6://announce-v6.syncthing.net:22026"},
 		GlobalAnnEnabled:        true,
 		LocalAnnEnabled:         true,
 		LocalAnnPort:            21025,
diff --git a/internal/config/testdata/v8.xml b/internal/config/testdata/v8.xml
new file mode 100644
index 000000000..0df863cc3
--- /dev/null
+++ b/internal/config/testdata/v8.xml
@@ -0,0 +1,12 @@
+<configuration version="8">
+    <folder id="test" path="testdata" ro="true" ignorePerms="false" rescanIntervalS="600">
+        <device id="AIR6LPZ-7K4PTTV-UXQSMUU-CPQ5YWH-OEDFIIQ-JUG777G-2YQXXR5-YD6AWQR"></device>
+        <device id="P56IOI7-MZJNU2Y-IQGDREY-DM2MGTI-MGL3BXN-PQ6W5BM-TBBZ4TJ-XZWICQ2"></device>
+    </folder>
+    <device id="AIR6LPZ-7K4PTTV-UXQSMUU-CPQ5YWH-OEDFIIQ-JUG777G-2YQXXR5-YD6AWQR" name="node one" compression="true">
+        <address>a</address>
+    </device>
+    <device id="P56IOI7-MZJNU2Y-IQGDREY-DM2MGTI-MGL3BXN-PQ6W5BM-TBBZ4TJ-XZWICQ2" name="node two" compression="true">
+        <address>b</address>
+    </device>
+</configuration>