diff --git a/internal/app/wireguard/wireguard.go b/internal/app/wireguard/wireguard.go
index 46ded30..eb76bc9 100644
--- a/internal/app/wireguard/wireguard.go
+++ b/internal/app/wireguard/wireguard.go
@@ -3,6 +3,7 @@ package wireguard
 import (
 	"context"
 	"log/slog"
+	"sync"
 	"time"
 
 	"github.com/h44z/wg-portal/internal/app"
@@ -76,6 +77,8 @@ type Manager struct {
 	db    InterfaceAndPeerDatabaseRepo
 	wg    InterfaceController
 	quick WgQuickController
+
+	userLockMap *sync.Map
 }
 
 func NewWireGuardManager(
@@ -86,11 +89,12 @@ func NewWireGuardManager(
 	db InterfaceAndPeerDatabaseRepo,
 ) (*Manager, error) {
 	m := &Manager{
-		cfg:   cfg,
-		bus:   bus,
-		wg:    wg,
-		db:    db,
-		quick: quick,
+		cfg:         cfg,
+		bus:         bus,
+		wg:          wg,
+		db:          db,
+		quick:       quick,
+		userLockMap: &sync.Map{},
 	}
 
 	m.connectToMessageBus()
@@ -117,6 +121,12 @@ func (m Manager) handleUserCreationEvent(user domain.User) {
 		return
 	}
 
+	_, loaded := m.userLockMap.LoadOrStore(user.Identifier, "create")
+	if loaded {
+		return // another goroutine is already handling this user
+	}
+	defer m.userLockMap.Delete(user.Identifier)
+
 	slog.Debug("handling new user event", "user", user.Identifier)
 
 	ctx := domain.SetUserInfo(context.Background(), domain.SystemAdminContextUserInfo())
@@ -132,6 +142,12 @@ func (m Manager) handleUserLoginEvent(userId domain.UserIdentifier) {
 		return
 	}
 
+	_, loaded := m.userLockMap.LoadOrStore(userId, "login")
+	if loaded {
+		return // another goroutine is already handling this user
+	}
+	defer m.userLockMap.Delete(userId)
+
 	userPeers, err := m.db.GetUserPeers(context.Background(), userId)
 	if err != nil {
 		slog.Error("failed to retrieve existing peers prior to default peer creation",
diff --git a/internal/app/wireguard/wireguard_peers.go b/internal/app/wireguard/wireguard_peers.go
index ade8fa4..2131323 100644
--- a/internal/app/wireguard/wireguard_peers.go
+++ b/internal/app/wireguard/wireguard_peers.go
@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"log/slog"
+	"slices"
 	"time"
 
 	"github.com/h44z/wg-portal/internal/app"
@@ -23,12 +24,24 @@ func (m Manager) CreateDefaultPeer(ctx context.Context, userId domain.UserIdenti
 		return fmt.Errorf("failed to fetch all interfaces: %w", err)
 	}
 
+	userPeers, err := m.db.GetUserPeers(context.Background(), userId)
+	if err != nil {
+		return fmt.Errorf("failed to retrieve existing peers prior to default peer creation: %w", err)
+	}
+
 	var newPeers []domain.Peer
 	for _, iface := range existingInterfaces {
 		if iface.Type != domain.InterfaceTypeServer {
 			continue // only create default peers for server interfaces
 		}
 
+		peerAlreadyCreated := slices.ContainsFunc(userPeers, func(peer domain.Peer) bool {
+			return peer.InterfaceIdentifier == iface.Identifier
+		})
+		if peerAlreadyCreated {
+			continue // skip creation if a peer already exists for this interface
+		}
+
 		peer, err := m.PreparePeer(ctx, iface.Identifier)
 		if err != nil {
 			return fmt.Errorf("failed to create default peer for interface %s: %w", iface.Identifier, err)
diff --git a/internal/config/config.go b/internal/config/config.go
index dedebac..44ef8e4 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -190,6 +190,8 @@ func GetConfig() (*Config, error) {
 		return nil, fmt.Errorf("failed to load config from yaml: %w", err)
 	}
 
+	cfg.Web.Sanitize()
+
 	return cfg, nil
 }
 
diff --git a/internal/config/web.go b/internal/config/web.go
index 1743305..e4d8dd3 100644
--- a/internal/config/web.go
+++ b/internal/config/web.go
@@ -1,5 +1,7 @@
 package config
 
+import "strings"
+
 // WebConfig contains the configuration for the web server.
 type WebConfig struct {
 	// RequestLogging enables logging of all HTTP requests.
@@ -26,3 +28,7 @@ type WebConfig struct {
 	// KeyFile is the path to the TLS certificate key file.
 	KeyFile string `yaml:"key_file"`
 }
+
+func (c *WebConfig) Sanitize() {
+	c.ExternalUrl = strings.TrimRight(c.ExternalUrl, "/")
+}