diff --git a/crates/defguard_common/src/db/models/device.rs b/crates/defguard_common/src/db/models/device.rs
index 65087a3408..ef2682aa58 100644
--- a/crates/defguard_common/src/db/models/device.rs
+++ b/crates/defguard_common/src/db/models/device.rs
@@ -27,7 +27,9 @@ use crate::{
             ModelError, WireguardNetwork,
             user::User,
             vpn_client_session::VpnClientSessionState,
-            wireguard::{LocationMfaMode, NetworkAddressError, ServiceLocationMode},
+            wireguard::{
+                LocationMfaMode, NetworkAddressError, ServiceLocationMode, WireguardNetworkError,
+            },
         },
     },
 };
@@ -539,9 +541,13 @@ pub enum DeviceError {
     #[error("Database error")]
     DatabaseError(#[from] sqlx::Error),
     #[error(transparent)]
+    ModelError(#[from] ModelError),
+    #[error(transparent)]
     NetworkIpAssignmentError(#[from] NetworkAddressError),
     #[error("Unexpected error: {0}")]
     Unexpected(String),
+    #[error("Network {0} is full, no IP addresses available for device")]
+    NetworkFull(String),
 }
 
 impl Device {
@@ -780,12 +786,23 @@ impl Device<Id> {
                 continue;
             }
 
-            // FIXME: don't ignore the error.
-            let Ok(wireguard_network_device) =
-                network.add_device_to_network(&mut *conn, self, None).await
-            else {
-                warn!("Failed to add device {self} to network {network}");
-                continue;
+            let wireguard_network_device = match network
+                .add_device_to_network(&mut *conn, self, None)
+                .await
+            {
+                Ok(device) => device,
+                Err(WireguardNetworkError::DeviceNotAllowed(_)) => {
+                    debug!("Device {self} is not allowed in network {network}, skipping");
+                    continue;
+                }
+                Err(WireguardNetworkError::DeviceError(DeviceError::NetworkFull(_))) => {
+                    warn!("Network {network} is full, no IP addresses available for device {self}");
+                    return Err(DeviceError::NetworkFull(network.name.clone()));
+                }
+                Err(err) => {
+                    warn!("Failed to add device {self} to network {network}: {err}");
+                    return Err(DeviceError::Unexpected(err.to_string()));
+                }
             };
 
             debug!(
@@ -846,7 +863,7 @@ impl Device<Id> {
     /// # Returns
     ///
     /// - `Ok(WireguardNetworkDevice)`: A new relation linking this device to its assigned IPs across all subnets.
-    /// - `Err(ModelError::CannotCreate)`: If any subnet lacks an available IP.
+    /// - `Err(DeviceError::NetworkFull)`: If any subnet lacks an available IP.
     pub async fn assign_next_network_ip(
         &self,
         transaction: &mut PgConnection,
@@ -854,7 +871,7 @@ impl Device<Id> {
         used_ips: &HashSet<IpAddr>,
         reserved_ips: Option<&[IpAddr]>,
         current_ips: Option<&[IpAddr]>,
-    ) -> Result<WireguardNetworkDevice, ModelError> {
+    ) -> Result<WireguardNetworkDevice, DeviceError> {
         debug!(
             "Assiging IP addresses for device: {} in network {}",
             self.name, network.name
@@ -899,7 +916,7 @@ impl Device<Id> {
                     "Failed to assign address for device {} in network {address:?}",
                     self.name,
                 );
-                ModelError::CannotCreate
+                DeviceError::NetworkFull(address.to_string())
             })?;
 
             // Otherwise, store the IP address
diff --git a/crates/defguard_common/src/db/models/wireguard.rs b/crates/defguard_common/src/db/models/wireguard.rs
index 23c20d659c..95134cdd6a 100644
--- a/crates/defguard_common/src/db/models/wireguard.rs
+++ b/crates/defguard_common/src/db/models/wireguard.rs
@@ -377,7 +377,7 @@ impl WireguardNetwork<Id> {
         &self,
         transaction: &mut PgConnection,
         user_id: Id,
-    ) -> Result<Vec<Device<Id>>, ModelError> {
+    ) -> Result<Vec<Device<Id>>, DeviceError> {
         debug!("Fetching all allowed devices for network {self}, user ID {user_id}");
         let devices =
             match self.get_allowed_groups(&mut *transaction).await? {
@@ -426,7 +426,7 @@ impl WireguardNetwork<Id> {
     pub async fn add_all_allowed_devices(
         &self,
         transaction: &mut PgConnection,
-    ) -> Result<(), ModelError> {
+    ) -> Result<(), DeviceError> {
         info!(
             "Assigning IPs in network {} for all existing devices ",
             self
diff --git a/crates/defguard_core/src/error.rs b/crates/defguard_core/src/error.rs
index 5e5edbdd0c..dc457ca4b1 100644
--- a/crates/defguard_core/src/error.rs
+++ b/crates/defguard_core/src/error.rs
@@ -89,6 +89,8 @@ pub enum WebError {
     #[error(transparent)]
     #[schema(value_type=Object)]
     StaticIpError(#[from] StaticIpError),
+    #[error("Network full: {0}")]
+    NetworkFull(String),
 }
 
 impl From<tonic::Status> for WebError {
@@ -122,6 +124,8 @@ impl From<DeviceError> for WebError {
             DeviceError::DatabaseError(_) => Self::DbError(error.to_string()),
             DeviceError::NetworkIpAssignmentError(_) => Self::ModelError(error.to_string()),
             DeviceError::Unexpected(_) => Self::Http(StatusCode::INTERNAL_SERVER_ERROR),
+            DeviceError::NetworkFull(_) => Self::NetworkFull(error.to_string()),
+            DeviceError::ModelError(_) => Self::ModelError(error.to_string()),
         }
     }
 }
diff --git a/crates/defguard_core/src/handlers/mod.rs b/crates/defguard_core/src/handlers/mod.rs
index 857e486b0b..7811bac66c 100644
--- a/crates/defguard_core/src/handlers/mod.rs
+++ b/crates/defguard_core/src/handlers/mod.rs
@@ -56,6 +56,12 @@ pub mod wireguard;
 pub mod worker;
 pub(crate) mod yubikey;
 
+#[derive(Serialize)]
+#[serde(rename_all = "snake_case")]
+pub enum WebErrorCode {
+    NetworkFull,
+}
+
 pub static SESSION_COOKIE_NAME: &str = "defguard_session";
 pub(crate) static SIGN_IN_COOKIE_NAME: &str = "defguard_sign_in";
 pub(crate) const SIGN_IN_COOKIE_MAX_AGE: time::Duration = time::Duration::minutes(10);
@@ -224,6 +230,13 @@ impl From<WebError> for ApiResponse {
                 error!(msg);
                 ApiResponse::new(json!({"msg": msg}), StatusCode::BAD_REQUEST)
             }
+            WebError::NetworkFull(msg) => {
+                warn!(msg);
+                ApiResponse::new(
+                    json!({"msg": msg, "code": WebErrorCode::NetworkFull}),
+                    StatusCode::BAD_REQUEST,
+                )
+            }
             WebError::TemplateError(err) => {
                 error!("Template error: {err}");
                 ApiResponse::new(
diff --git a/crates/defguard_core/src/handlers/network_devices.rs b/crates/defguard_core/src/handlers/network_devices.rs
index 0c03d194b8..d32bd05829 100644
--- a/crates/defguard_core/src/handlers/network_devices.rs
+++ b/crates/defguard_core/src/handlers/network_devices.rs
@@ -349,19 +349,21 @@ pub(crate) async fn find_available_ips(
     }
 
     transaction.commit().await?;
-    if split_ips.len() == network.address.len() {
-        debug!(
-            "Found addresses {:?} for new device i network {} ({:?})",
-            split_ips, network.name, network.address
-        );
-        Ok(ApiResponse::json(split_ips, StatusCode::OK))
-    } else {
+    if split_ips.len() != network.address.len() {
         warn!(
             "Failed to find available IPs for new device in network {} ({:?})",
             network.name, network.address
         );
-        Ok(ApiResponse::with_status(StatusCode::NOT_FOUND))
+        return Err(WebError::NetworkFull(format!(
+            "Network {} is full, no IP addresses available",
+            network.name
+        )));
     }
+    debug!(
+        "Found addresses {:?} for new device in network {} ({:?})",
+        split_ips, network.name, network.address
+    );
+    Ok(ApiResponse::json(split_ips, StatusCode::OK))
 }
 
 #[derive(Serialize, Deserialize, Debug)]
diff --git a/web/messages/en/api-error.json b/web/messages/en/api-error.json
new file mode 100644
index 0000000000..a049422d23
--- /dev/null
+++ b/web/messages/en/api-error.json
@@ -0,0 +1,4 @@
+{
+  "$schema": "https://inlang.com/schema/inlang-message-format",
+  "api_error_network_full": "Network is full, no IP addresses available"
+}
diff --git a/web/messages/en/location.json b/web/messages/en/location.json
index c80b5f1a3b..2923ef87c2 100644
--- a/web/messages/en/location.json
+++ b/web/messages/en/location.json
@@ -9,6 +9,7 @@
   "location_delete_failed": "Failed to delete location",
   "network_device_delete_success": "Network device deleted",
   "network_device_delete_failed": "Failed to delete network device",
+  "network_device_add_error": "Failed to load network data for adding device",
   "location_edit_failed": "Failed to update location",
   "location_edit_addresses_rewrite_warning": "Changing the Gateway VPN IP address or netmask will automatically reassign any device addresses that fall outside the new network range to a randomly selected available IP address."
 }
diff --git a/web/project.inlang/settings.json b/web/project.inlang/settings.json
index 61308a6bc2..6fc3720e14 100644
--- a/web/project.inlang/settings.json
+++ b/web/project.inlang/settings.json
@@ -27,7 +27,8 @@
       "./messages/{locale}/settings.json",
       "./messages/{locale}/gateway_wizard.json",
       "./messages/{locale}/initial_wizard.json",
-      "./messages/{locale}/migration_wizard.json"
+      "./messages/{locale}/migration_wizard.json",
+      "./messages/{locale}/api-error.json"
     ]
   }
 }
diff --git a/web/src/pages/NetworkDevicesPage/NetworkDevicesTable.tsx b/web/src/pages/NetworkDevicesPage/NetworkDevicesTable.tsx
index 6f8ef16d42..29df046ae1 100644
--- a/web/src/pages/NetworkDevicesPage/NetworkDevicesTable.tsx
+++ b/web/src/pages/NetworkDevicesPage/NetworkDevicesTable.tsx
@@ -5,11 +5,17 @@ import {
   getSortedRowModel,
   useReactTable,
 } from '@tanstack/react-table';
+import type { AxiosError } from 'axios';
 import { orderBy } from 'lodash-es';
 import { useMemo } from 'react';
 import { m } from '../../paraglide/messages';
 import api from '../../shared/api/api';
-import { LocationMfaMode, type NetworkDevice } from '../../shared/api/types';
+import { getApiErrorMessage } from '../../shared/api/apiErrorMessages';
+import {
+  type ApiError,
+  LocationMfaMode,
+  type NetworkDevice,
+} from '../../shared/api/types';
 import { Badge } from '../../shared/defguard-ui/components/Badge/Badge';
 import { Button } from '../../shared/defguard-ui/components/Button/Button';
 import type { ButtonProps } from '../../shared/defguard-ui/components/Button/types';
@@ -24,6 +30,7 @@ import { TableBody } from '../../shared/defguard-ui/components/table/TableBody/T
 import { TableCell } from '../../shared/defguard-ui/components/table/TableCell/TableCell';
 import { TableEditCell } from '../../shared/defguard-ui/components/table/TableEditCell/TableEditCell';
 import { TableTop } from '../../shared/defguard-ui/components/table/TableTop/TableTop';
+import { Snackbar } from '../../shared/defguard-ui/providers/snackbar/snackbar';
 import { ThemeSize } from '../../shared/defguard-ui/types';
 import { openModal } from '../../shared/hooks/modalControls/modalsSubjects';
 import { ModalName } from '../../shared/hooks/modalControls/modalTypes';
@@ -63,6 +70,15 @@ export const NetworkDevicesTable = ({ networkDevices }: Props) => {
         reservedNames,
       });
     },
+    onError: (e) => {
+      console.error(e);
+      const code = (e as AxiosError<ApiError>).response?.data?.code;
+      if (code) {
+        Snackbar.error(getApiErrorMessage(code));
+      } else {
+        Snackbar.error(m.network_device_add_error());
+      }
+    },
   });
 
   const addButtonProps = useMemo(
diff --git a/web/src/shared/api/apiErrorMessages.ts b/web/src/shared/api/apiErrorMessages.ts
new file mode 100644
index 0000000000..0a4a2dde68
--- /dev/null
+++ b/web/src/shared/api/apiErrorMessages.ts
@@ -0,0 +1,7 @@
+import { m } from '../../paraglide/messages';
+import type { ApiErrorMessageKey, WebErrorCode } from './types';
+
+export function getApiErrorMessage(code: WebErrorCode): string {
+  const key: ApiErrorMessageKey = `api_error_${code}`;
+  return (m as Record<ApiErrorMessageKey, () => string>)[key]();
+}
diff --git a/web/src/shared/api/types.ts b/web/src/shared/api/types.ts
index ef0fac4845..9cc252d782 100644
--- a/web/src/shared/api/types.ts
+++ b/web/src/shared/api/types.ts
@@ -305,9 +305,18 @@ export interface MfaFinishResponse {
   user?: User;
 }
 
+export const WebErrorCode = {
+  NetworkFull: 'network_full',
+} as const;
+
+export type WebErrorCode = (typeof WebErrorCode)[keyof typeof WebErrorCode];
+
+export type ApiErrorMessageKey = `api_error_${WebErrorCode}`;
+
 export interface ApiError {
   msg?: string;
   message?: string;
+  code?: WebErrorCode;
 }
 
 export interface AppInfoExceededLimits {
diff --git a/web/src/shared/components/modals/AddUserDeviceModal/steps/AddDeviceModalManualSetupStep/AddDeviceModalManualSetupStep.tsx b/web/src/shared/components/modals/AddUserDeviceModal/steps/AddDeviceModalManualSetupStep/AddDeviceModalManualSetupStep.tsx
index 36203d2816..868db1e14d 100644
--- a/web/src/shared/components/modals/AddUserDeviceModal/steps/AddDeviceModalManualSetupStep/AddDeviceModalManualSetupStep.tsx
+++ b/web/src/shared/components/modals/AddUserDeviceModal/steps/AddDeviceModalManualSetupStep/AddDeviceModalManualSetupStep.tsx
@@ -10,8 +10,10 @@ import { useMutation } from '@tanstack/react-query';
 import type { AxiosError } from 'axios';
 import { useMemo } from 'react';
 import api from '../../../../../api/api';
+import { getApiErrorMessage } from '../../../../../api/apiErrorMessages';
 import type { ApiError } from '../../../../../api/types';
 import { SizedBox } from '../../../../../defguard-ui/components/SizedBox/SizedBox';
+import { Snackbar } from '../../../../../defguard-ui/providers/snackbar/snackbar';
 import { ThemeSpacing } from '../../../../../defguard-ui/types';
 import { patternValidWireguardKey } from '../../../../../patterns';
 import { generateWGKeys } from '../../../../../utils/generateWGKeys';
@@ -107,6 +109,11 @@ export const AddDeviceModalManualSetupStep = () => {
               },
             },
           });
+        } else {
+          const code = (e as AxiosError<ApiError>).response?.data?.code;
+          if (code) {
+            Snackbar.error(getApiErrorMessage(code));
+          }
         }
       });
 
@@ -114,6 +121,7 @@ export const AddDeviceModalManualSetupStep = () => {
 
       if (!createResponse.data.configs.length) {
         useAddUserDeviceModal.getState().close();
+        return;
       }
 
       useAddUserDeviceModal.setState({