Add global MTU setting

src-tauri/Cargo.toml

@@ -4,7 +4,7 @@ default-members = [".", "cli"]
 
 [workspace.dependencies]
 clap = { version = "4.5", features = ["cargo", "derive", "env"] }
-defguard_wireguard_rs = { git = "https://github.com/DefGuard/wireguard-rs", rev = "886186c1e088e4805ab8049436c28cf3ea26d727" }
+defguard_wireguard_rs = { git = "https://github.com/DefGuard/wireguard-rs", rev = "c99c0b209b19d9ce82e0f5d0d727261f8f9916b3" }
 dirs-next = "2.0"
 prost = "0.14"
 reqwest = { version = "0.12", features = ["cookies", "json"] }

src-tauri/src/app_config.rs

@@ -71,6 +71,8 @@ pub struct AppConfig {
     pub log_level: LevelFilter,
     /// In seconds. How much time after last network activity the connection is automatically dropped.
     pub peer_alive_period: u32,
+    /// Maximal transmission unit. 0 means default value.
+    pub mtu: u32,
 }
 
 // Important: keep in sync with client store default in frontend
@@ -82,6 +84,7 @@ impl Default for AppConfig {
             tray_theme: AppTrayTheme::Color,
             log_level: LevelFilter::Info,
             peer_alive_period: 300,
+            mtu: 0,
         }
     }
 }
@@ -130,4 +133,14 @@ impl AppConfig {
             }
         }
     }
+
+    /// Wraps MTU in an Option. We don't store Option directly in AppConfig to avoid struct-patch
+    /// ambiguity when applying updates coming from the frontend. An incoming MTU value of 0 is
+    /// interpreted as a request to fall back to the default.
+    pub fn get_mtu(&self) -> Option<u32> {
+        match self.mtu {
+            0 => None,
+            v => Some(v),
+        }
+    }
 }

src-tauri/src/database/models/location.rs

@@ -257,7 +257,7 @@ impl Location<Id> {
     }
 
     #[cfg(not(target_os = "macos"))]
-    pub(crate) async fn interface_configurarion<'e, E>(
+    pub(crate) async fn interface_configuration<'e, E>(
         &self,
         executor: E,
         interface_name: String,

src-tauri/src/service/mod.rs

@@ -575,6 +575,7 @@ impl From<InterfaceConfiguration> for proto::InterfaceConfig {
                 .join(","),
             port: u32::from(config.port),
             peers: config.peers.into_iter().map(Into::into).collect(),
+            mtu: config.mtu,
         }
     }
 }
@@ -592,7 +593,7 @@ impl From<proto::InterfaceConfig> for InterfaceConfiguration {
             addresses,
             port: config.port as u16,
             peers: config.peers.into_iter().map(Into::into).collect(),
-            mtu: None,
+            mtu: config.mtu,
         }
     }
 }

src-tauri/src/utils.rs

@@ -59,6 +59,7 @@ pub(crate) async fn setup_interface(
     location: &Location<Id>,
     name: &str,
     preshared_key: Option<String>,
+    mtu: Option<u32>,
     pool: &DbPool,
 ) -> Result<String, Error> {
     debug!("Setting up interface for location: {location}");
@@ -76,9 +77,10 @@ pub(crate) async fn setup_interface(
     };
     debug!("Found free port: {port} for interface {interface_name}.");
 
-    let interface_config = location
-        .interface_configurarion(pool, interface_name.clone(), preshared_key)
+    let mut interface_config = location
+        .interface_configuration(pool, interface_name.clone(), preshared_key)
         .await?;
+    interface_config.mtu = mtu;
     debug!("Creating interface for location {location} with configuration {interface_config:?}");
     let request = CreateInterfaceRequest {
         config: Some(interface_config.clone().into()),
@@ -120,6 +122,7 @@ pub(crate) async fn setup_interface(
     location: &Location<Id>,
     name: &str,
     preshared_key: Option<String>,
+    _mtu: Option<u32>,
     pool: &DbPool,
 ) -> Result<String, Error> {
     debug!("Setting up interface for location: {location}");
@@ -307,7 +310,11 @@ pub fn get_service_log_dir() -> &'static Path {
 }
 
 /// Setup client interface
-pub async fn setup_interface_tunnel(tunnel: &Tunnel<Id>, name: &str) -> Result<String, Error> {
+pub async fn setup_interface_tunnel(
+    tunnel: &Tunnel<Id>,
+    name: &str,
+    mtu: Option<u32>,
+) -> Result<String, Error> {
     debug!("Setting up interface for tunnel {tunnel}");
     let interface_name = get_interface_name(name);
     // prepare peer config
@@ -397,7 +404,7 @@ pub async fn setup_interface_tunnel(tunnel: &Tunnel<Id>, name: &str) -> Result<S
         addresses,
         port,
         peers: vec![peer.clone()],
-        mtu: None,
+        mtu,
     };
     debug!("Creating interface {interface_config:?}");
     let request = CreateInterfaceRequest {
@@ -576,7 +583,9 @@ pub(crate) async fn handle_connection_for_location(
 ) -> Result<(), Error> {
     debug!("Setting up the connection for location {}", location.name);
     let state = handle.state::<AppState>();
-    let interface_name = setup_interface(location, &location.name, preshared_key, &DB_POOL).await?;
+    let mtu = state.app_config.lock().unwrap().get_mtu();
+    let interface_name =
+        setup_interface(location, &location.name, preshared_key, mtu, &DB_POOL).await?;
     state
         .add_connection(location.id, &interface_name, ConnectionType::Location)
         .await;
@@ -607,7 +616,8 @@ pub(crate) async fn handle_connection_for_tunnel(
 ) -> Result<(), Error> {
     debug!("Setting up the connection for tunnel: {}", tunnel.name);
     let state = handle.state::<AppState>();
-    let interface_name = setup_interface_tunnel(tunnel, &tunnel.name).await?;
+    let mtu = state.app_config.lock().unwrap().get_mtu();
+    let interface_name = setup_interface_tunnel(tunnel, &tunnel.name, mtu).await?;
     state
         .add_connection(tunnel.id, &interface_name, ConnectionType::Tunnel)
         .await;

src/i18n/en/index.ts

@@ -161,6 +161,11 @@ If you are an admin/devops - all your customers (instances) and all their tunnel
                 helper:
                   'If active connection exceeds given time without making an handshake with the server. The connection will be considered invalid and disconnected automatically.',
               },
+              mtu: {
+                title: 'MTU (Maximum Transmission Unit)',
+                helper:
+                  'MTU sets the largest packet size sent through the network. Lowering it can improve connection stability in restrictive or unreliable ISP networks. The default value on most systems is 1500. Try lowering it to 1300-1400 if you encounter ISP-related issues. 0 = default.',
+              },
               tray: {
                 title: 'System tray',
                 label: 'Tray icon theme',

src/i18n/i18n-types.ts

@@ -376,6 +376,16 @@ type RootTranslation = {
 								 */
 								helper: string
 							}
+							mtu: {
+								/**
+								 * M​T​U​ ​(​M​a​x​i​m​u​m​ ​T​r​a​n​s​m​i​s​s​i​o​n​ ​U​n​i​t​)
+								 */
+								title: string
+								/**
+								 * M​T​U​ ​s​e​t​s​ ​t​h​e​ ​l​a​r​g​e​s​t​ ​p​a​c​k​e​t​ ​s​i​z​e​ ​s​e​n​t​ ​t​h​r​o​u​g​h​ ​t​h​e​ ​n​e​t​w​o​r​k​.​ ​L​o​w​e​r​i​n​g​ ​i​t​ ​c​a​n​ ​i​m​p​r​o​v​e​ ​c​o​n​n​e​c​t​i​o​n​ ​s​t​a​b​i​l​i​t​y​ ​i​n​ ​r​e​s​t​r​i​c​t​i​v​e​ ​o​r​ ​u​n​r​e​l​i​a​b​l​e​ ​I​S​P​ ​n​e​t​w​o​r​k​s​.​ ​T​h​e​ ​d​e​f​a​u​l​t​ ​v​a​l​u​e​ ​o​n​ ​m​o​s​t​ ​s​y​s​t​e​m​s​ ​i​s​ ​1​5​0​0​.​ ​T​r​y​ ​l​o​w​e​r​i​n​g​ ​i​t​ ​t​o​ ​1​3​0​0​-​1​4​0​0​ ​i​f​ ​y​o​u​ ​e​n​c​o​u​n​t​e​r​ ​I​S​P​-​r​e​l​a​t​e​d​ ​i​s​s​u​e​s​.​ ​0​ ​=​ ​d​e​f​a​u​l​t​.
+								 */
+								helper: string
+							}
 							tray: {
 								/**
 								 * S​y​s​t​e​m​ ​t​r​a​y
@@ -2066,6 +2076,16 @@ export type TranslationFunctions = {
 								 */
 								helper: () => LocalizedString
 							}
+							mtu: {
+								/**
+								 * MTU (Maximum Transmission Unit)
+								 */
+								title: () => LocalizedString
+								/**
+								 * MTU sets the largest packet size sent through the network. Lowering it can improve connection stability in restrictive or unreliable ISP networks. The default value on most systems is 1500. Try lowering it to 1300-1400 if you encounter ISP-related issues. 0 = default.
+								 */
+								helper: () => LocalizedString
+							}
 							tray: {
 								/**
 								 * System tray

src/pages/client/clientAPI/types.ts

@@ -80,6 +80,7 @@ export type AppConfig = {
   tray_theme: TrayIconTheme;
   check_for_updates: boolean;
   peer_alive_period: number;
+  mtu: number;
 };
 
 export type PlatformInfo = {

src/pages/client/hooks/useClientStore.tsx

@@ -35,6 +35,7 @@ const defaultValues: StoreValues = {
     tray_theme: 'color',
     check_for_updates: true,
     peer_alive_period: 300,
+    mtu: 0,
   },
   platformInfo: {
     client_version: '',

src/pages/client/pages/ClientSettingsPage/components/GlobalSettingsTab/GlobalSettingsTab.tsx

@@ -81,6 +81,12 @@ export const GlobalSettingsTab = () => {
             required_error: LL.form.errors.required(),
           })
           .gte(120, LL.form.errors.minValue({ min: 120 })),
+        mtu: z
+          .number({
+            invalid_type_error: LL.form.errors.required(),
+            required_error: LL.form.errors.required(),
+          })
+          .lte(65535, LL.form.errors.maxValue({ max: 65535 })),
       }),
     [LL.form.errors],
   );
@@ -139,6 +145,15 @@ export const GlobalSettingsTab = () => {
         </header>
         <FormInput controller={{ control, name: 'peer_alive_period' }} type="number" />
       </section>
+      <section>
+        <header>
+          <h2>{localLL.mtu.title()}</h2>
+          <Helper initialPlacement="right">
+            <p>{localLL.mtu.helper()}</p>
+          </Helper>
+        </header>
+        <FormInput controller={{ control, name: 'mtu' }} type="number" />
+      </section>
     </form>
   );
 };