diff --git a/internal/wireguard/functional_test.go b/internal/wireguard/functional_test.go
new file mode 100644
index 0000000..be9ecc4
--- /dev/null
+++ b/internal/wireguard/functional_test.go
@@ -0,0 +1,175 @@
+//go:build functional && linux
+// +build functional,linux
+
+// Run integrations tests as root!
+
+package wireguard
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"strconv"
+	"strings"
+	"testing"
+
+	"github.com/h44z/wg-portal/internal/lowlevel"
+	"github.com/h44z/wg-portal/internal/persistence"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"golang.zx2c4.com/wireguard/wgctrl"
+)
+
+// setup WireGuard manager with no linked store
+func setup(t *testing.T) Manager {
+	if getProcessOwner() != "root" {
+		t.Fatalf("this tests need to be executed as root user")
+	}
+
+	wg, err := wgctrl.New()
+	require.NoError(t, err)
+
+	nl := &lowlevel.NetlinkManager{}
+
+	manager, err := NewPersistentManager(wg, nl, nil) // No Store, all in memory
+	require.NoError(t, err)
+
+	return manager
+}
+
+func getProcessOwner() string {
+	stdout, err := exec.Command("ps", "-o", "user=", "-p", strconv.Itoa(os.Getpid())).Output()
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+	return strings.TrimSpace(string(stdout))
+}
+
+func TestWireGuardCreateInterface(t *testing.T) {
+	mgr := setup(t)
+
+	interfaceName := persistence.InterfaceIdentifier("wg_test_001")
+	defer mgr.DeleteInterface(interfaceName)
+
+	err := mgr.CreateInterface(interfaceName)
+	assert.NoError(t, err)
+
+	// Validate that the interface has been created
+	cmd := exec.Command("ip", "addr")
+	out, err := cmd.CombinedOutput()
+	assert.NoError(t, err)
+	assert.Contains(t, string(out), interfaceName)
+}
+
+func TestWireGuardDeleteInterface(t *testing.T) {
+	mgr := setup(t)
+
+	interfaceName := persistence.InterfaceIdentifier("wg_test_001")
+	defer mgr.DeleteInterface(interfaceName)
+
+	err := mgr.CreateInterface(interfaceName)
+	assert.NoError(t, err)
+
+	err = mgr.DeleteInterface(interfaceName)
+	assert.NoError(t, err)
+
+	// Validate that the interface has been deleted
+	cmd := exec.Command("ip", "addr")
+	out, err := cmd.CombinedOutput()
+	assert.NoError(t, err)
+	assert.NotContains(t, string(out), interfaceName)
+}
+
+func TestWireGuardUpdateInterface(t *testing.T) {
+	mgr := setup(t)
+
+	interfaceName := persistence.InterfaceIdentifier("wg_test_001")
+	defer mgr.DeleteInterface(interfaceName)
+
+	err := mgr.CreateInterface(interfaceName)
+
+	keys, err := mgr.GetFreshKeypair()
+	assert.NoError(t, err)
+	cfg := &persistence.InterfaceConfig{
+		Identifier: interfaceName,
+		KeyPair:    keys,
+		ListenPort: 12567,
+		Mtu:        1420,
+		AddressStr: "10.98.87.76/24",
+		Enabled:    true,
+	}
+	err = mgr.UpdateInterface(interfaceName, cfg)
+	assert.NoError(t, err)
+
+	// Validate that the interface has been updated
+	cmd := exec.Command("ip", "addr")
+	out, err := cmd.CombinedOutput()
+	assert.NoError(t, err)
+	assert.Contains(t, string(out), interfaceName)
+	assert.Contains(t, string(out), "10.98.87.76")
+}
+
+func TestWireGuardDisableInterface(t *testing.T) {
+	mgr := setup(t)
+
+	interfaceName := persistence.InterfaceIdentifier("wg_test_001")
+	defer mgr.DeleteInterface(interfaceName)
+
+	err := mgr.CreateInterface(interfaceName)
+
+	keys, err := mgr.GetFreshKeypair()
+	assert.NoError(t, err)
+	cfg := &persistence.InterfaceConfig{
+		Identifier: interfaceName,
+		KeyPair:    keys,
+		ListenPort: 12567,
+		Mtu:        1420,
+		AddressStr: "10.98.87.76/24",
+		Enabled:    false,
+	}
+	err = mgr.UpdateInterface(interfaceName, cfg)
+	assert.NoError(t, err)
+
+	// Validate that the interface has been updated
+	cmd := exec.Command("ip", "addr")
+	out, err := cmd.CombinedOutput()
+	assert.NoError(t, err)
+	assert.Contains(t, string(out), interfaceName)
+	assert.Contains(t, string(out), "10.98.87.76")
+	assert.Contains(t, string(out), "state DOWN")
+}
+
+func TestWireGuardEnableInterface(t *testing.T) {
+	mgr := setup(t)
+
+	interfaceName := persistence.InterfaceIdentifier("wg_test_001")
+	defer mgr.DeleteInterface(interfaceName)
+
+	err := mgr.CreateInterface(interfaceName)
+
+	keys, err := mgr.GetFreshKeypair()
+	assert.NoError(t, err)
+	cfg := &persistence.InterfaceConfig{
+		Identifier: interfaceName,
+		KeyPair:    keys,
+		ListenPort: 12567,
+		Mtu:        1420,
+		AddressStr: "10.98.87.76/24",
+		Enabled:    false,
+	}
+	err = mgr.UpdateInterface(interfaceName, cfg)
+	assert.NoError(t, err)
+
+	cfg.Enabled = true
+	err = mgr.UpdateInterface(interfaceName, cfg)
+	assert.NoError(t, err)
+
+	// Validate that the interface has been updated
+	cmd := exec.Command("ip", "addr")
+	out, err := cmd.CombinedOutput()
+	assert.NoError(t, err)
+	assert.Contains(t, string(out), interfaceName)
+	assert.Contains(t, string(out), "10.98.87.76")
+	assert.Contains(t, string(out), "state U") // Can be UNKNOWN or UP
+}
diff --git a/internal/wireguard/wireguard.go b/internal/wireguard/wireguard.go
index 1e11f21..cea4179 100644
--- a/internal/wireguard/wireguard.go
+++ b/internal/wireguard/wireguard.go
@@ -136,8 +136,10 @@
 	if err != nil {
 		return errors.WithMessage(err, "failed to open low level interface")
 	}
-	if err := m.nl.LinkSetMTU(link, cfg.Mtu); err != nil {
-		return errors.WithMessage(err, "failed to set MTU")
+	if cfg.Mtu != 0 {
+		if err := m.nl.LinkSetMTU(link, cfg.Mtu); err != nil {
+			return errors.WithMessage(err, "failed to set MTU")
+		}
 	}
 	addresses, err := parseIpAddressString(cfg.AddressStr)
 	if err != nil {
diff --git a/internal/wireguard/wireguard_test.go b/internal/wireguard/wireguard_test.go
index ba141ae..a3e17a6 100644
--- a/internal/wireguard/wireguard_test.go
+++ b/internal/wireguard/wireguard_test.go
@@ -532,15 +532,15 @@
 				interfaces: map[persistence.InterfaceIdentifier]*persistence.InterfaceConfig{"wg0": {}},
 				peers: map[persistence.InterfaceIdentifier]map[persistence.PeerIdentifier]*persistence.PeerConfig{
 					"wg0": {
-						"peer0": &persistence.PeerConfig{Interface: &persistence.PeerInterfaceConfig{Identifier: "wg0"}},
-						"peer1": &persistence.PeerConfig{Interface: &persistence.PeerInterfaceConfig{Identifier: "wg1"}},
+						"peer0": &persistence.PeerConfig{Identifier: "peer0", Interface: &persistence.PeerInterfaceConfig{Identifier: "wg0"}},
+						"peer1": &persistence.PeerConfig{Identifier: "peer1", Interface: &persistence.PeerInterfaceConfig{Identifier: "wg1"}},
 					},
 				},
 			},
 			interfaceId: "wg0",
 			want: []*persistence.PeerConfig{
-				{Interface: &persistence.PeerInterfaceConfig{Identifier: "wg0"}},
-				{Interface: &persistence.PeerInterfaceConfig{Identifier: "wg1"}},
+				{Identifier: "peer0", Interface: &persistence.PeerInterfaceConfig{Identifier: "wg0"}},
+				{Identifier: "peer1", Interface: &persistence.PeerInterfaceConfig{Identifier: "wg1"}},
 			},
 			wantErr: false,
 		},