diff --git a/web/src/pages/UsersOverviewPage/UsersTable.tsx b/web/src/pages/UsersOverviewPage/UsersTable.tsx
index 1e0114c116..a343c1432c 100644
--- a/web/src/pages/UsersOverviewPage/UsersTable.tsx
+++ b/web/src/pages/UsersOverviewPage/UsersTable.tsx
@@ -439,6 +439,7 @@ export const UsersTable = () => {
       device: Device,
       username: string,
       reservedDeviceNames: string[],
+      reservedPubkeys: string[],
     ): MenuItemsGroup[] => [
       {
         items: [
@@ -449,6 +450,7 @@ export const UsersTable = () => {
               openModal(ModalName.EditUserDevice, {
                 device,
                 reservedNames: reservedDeviceNames,
+                reservedPubkeys,
                 username,
               });
             },
@@ -508,6 +510,7 @@ export const UsersTable = () => {
     (row: Row<RowData>, isLast = false) => {
       const username = row.original.username;
       const reservedDeviceNames = row.original.devices.map((d) => d.name);
+      const reservedPubkeys = row.original.devices.map((d) => d.wireguard_pubkey);
       return row.original.devices.map((device, deviceIndex) => {
         const lastRow = isLast && deviceIndex === row.original.devices.length - 1;
         const latestNetwork = orderBy(
@@ -523,7 +526,12 @@ export const UsersTable = () => {
         const connectionDate = latestNetwork?.last_connected_at
           ? displayDate(latestNetwork.last_connected_at)
           : neverConnected;
-        const menuItems = makeDeviceRowMenu(device, username, reservedDeviceNames);
+        const menuItems = makeDeviceRowMenu(
+          device,
+          username,
+          reservedDeviceNames,
+          reservedPubkeys,
+        );
         return (
           <TableRowContainer
             className={clsx({ last: lastRow })}
diff --git a/web/src/pages/user-profile/UserProfilePage/tabs/ProfileAuthKeysTab/ProfileAuthKeysTable.tsx b/web/src/pages/user-profile/UserProfilePage/tabs/ProfileAuthKeysTab/ProfileAuthKeysTable.tsx
index bfffe0dc1d..761d365e5d 100644
--- a/web/src/pages/user-profile/UserProfilePage/tabs/ProfileAuthKeysTab/ProfileAuthKeysTable.tsx
+++ b/web/src/pages/user-profile/UserProfilePage/tabs/ProfileAuthKeysTab/ProfileAuthKeysTable.tsx
@@ -176,6 +176,7 @@ export const ProfileAuthKeysTable = () => {
                       id: rowData.id,
                       name: rowData.name,
                       username,
+                      reservedNames: mapped.map((k) => k.name),
                     });
                   },
                 },
@@ -198,7 +199,7 @@ export const ProfileAuthKeysTable = () => {
         },
       }),
     ],
-    [deleteAuthKey, username, writeToClipboard],
+    [deleteAuthKey, username, writeToClipboard, mapped.map],
   );
 
   const table = useReactTable({
diff --git a/web/src/pages/user-profile/UserProfilePage/tabs/ProfileAuthKeysTab/modals/RenameAuthKeyModal/RenameAuthKeyModal.tsx b/web/src/pages/user-profile/UserProfilePage/tabs/ProfileAuthKeysTab/modals/RenameAuthKeyModal/RenameAuthKeyModal.tsx
index 15b85b119b..34f2fde39c 100644
--- a/web/src/pages/user-profile/UserProfilePage/tabs/ProfileAuthKeysTab/modals/RenameAuthKeyModal/RenameAuthKeyModal.tsx
+++ b/web/src/pages/user-profile/UserProfilePage/tabs/ProfileAuthKeysTab/modals/RenameAuthKeyModal/RenameAuthKeyModal.tsx
@@ -1,6 +1,6 @@
 import { useStore } from '@tanstack/react-form';
 import { useMutation } from '@tanstack/react-query';
-import { useEffect, useState } from 'react';
+import { useEffect, useMemo, useState } from 'react';
 import z from 'zod';
 import { m } from '../../../../../../../paraglide/messages';
 import api from '../../../../../../../shared/api/api';
@@ -50,11 +50,21 @@ export const RenameAuthKeyModal = () => {
   );
 };
 
-const formSchema = z.object({
-  name: z.string().trim().min(1, m.form_error_required()),
-});
+const getFormSchema = (reservedNames: string[]) =>
+  z.object({
+    name: z
+      .string()
+      .trim()
+      .min(1, m.form_error_required())
+      .refine((val) => !reservedNames.includes(val), m.form_error_name_reserved()),
+  });
+
+const ModalContent = ({ id, name, username, reservedNames }: OpenAuthKeyRenameModal) => {
+  const formSchema = useMemo(
+    () => getFormSchema(reservedNames.filter((n) => n !== name)),
+    [reservedNames, name],
+  );
 
-const ModalContent = ({ id, name, username }: OpenAuthKeyRenameModal) => {
   const { mutateAsync } = useMutation({
     mutationFn: api.user.renameAuthKey,
     meta: {
diff --git a/web/src/pages/user-profile/UserProfilePage/tabs/ProfileDevicesTab/components/ProfileDevicesTable/ProfileDevicesTable.tsx b/web/src/pages/user-profile/UserProfilePage/tabs/ProfileDevicesTab/components/ProfileDevicesTable/ProfileDevicesTable.tsx
index a8047c69e0..a775dd3bf4 100644
--- a/web/src/pages/user-profile/UserProfilePage/tabs/ProfileDevicesTab/components/ProfileDevicesTable/ProfileDevicesTable.tsx
+++ b/web/src/pages/user-profile/UserProfilePage/tabs/ProfileDevicesTab/components/ProfileDevicesTable/ProfileDevicesTable.tsx
@@ -93,6 +93,10 @@ const DevicesTable = ({ rowData }: { rowData: RowData[] }) => {
   const username = user.username;
 
   const reservedNames = useMemo(() => rowData.map((row) => row.name), [rowData]);
+  const reservedPubkeys = useMemo(
+    () => rowData.map((row) => row.wireguard_pubkey),
+    [rowData],
+  );
 
   const addDeviceProps = useMemo(
     (): ButtonProps => ({
@@ -121,6 +125,7 @@ const DevicesTable = ({ rowData }: { rowData: RowData[] }) => {
             openModal(ModalName.EditUserDevice, {
               device: row,
               reservedNames: reservedNames,
+              reservedPubkeys: reservedPubkeys,
               username,
             });
           },
@@ -177,7 +182,7 @@ const DevicesTable = ({ rowData }: { rowData: RowData[] }) => {
       );
       return [{ items }];
     },
-    [reservedNames, username, isAdmin],
+    [reservedNames, username, isAdmin, reservedPubkeys],
   );
 
   const tableColumns = useMemo(
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 2b178dbae5..36203d2816 100644
--- a/web/src/shared/components/modals/AddUserDeviceModal/steps/AddDeviceModalManualSetupStep/AddDeviceModalManualSetupStep.tsx
+++ b/web/src/shared/components/modals/AddUserDeviceModal/steps/AddDeviceModalManualSetupStep/AddDeviceModalManualSetupStep.tsx
@@ -7,8 +7,10 @@ import { formChangeLogic } from '../../../../../formLogic';
 import './style.scss';
 import { useStore } from '@tanstack/react-form';
 import { useMutation } from '@tanstack/react-query';
+import type { AxiosError } from 'axios';
 import { useMemo } from 'react';
 import api from '../../../../../api/api';
+import type { ApiError } from '../../../../../api/types';
 import { SizedBox } from '../../../../../defguard-ui/components/SizedBox/SizedBox';
 import { ThemeSpacing } from '../../../../../defguard-ui/types';
 import { patternValidWireguardKey } from '../../../../../patterns';
@@ -79,7 +81,7 @@ export const AddDeviceModalManualSetupStep = () => {
       onSubmit: formSchema,
       onChange: formSchema,
     },
-    onSubmit: async ({ value }) => {
+    onSubmit: async ({ value, formApi }) => {
       let publicKey: string;
       let privateKey: string | undefined;
 
@@ -95,8 +97,21 @@ export const AddDeviceModalManualSetupStep = () => {
         name: value.name,
         username,
         wireguard_pubkey: publicKey,
+      }).catch((e: AxiosError<ApiError>) => {
+        const msg = e.response?.data.msg;
+        if (msg?.includes('already exists')) {
+          formApi.setErrorMap({
+            onSubmit: {
+              fields: {
+                publicKey: m.form_error_key_exists(),
+              },
+            },
+          });
+        }
       });
 
+      if (!createResponse) return;
+
       if (!createResponse.data.configs.length) {
         useAddUserDeviceModal.getState().close();
       }
diff --git a/web/src/shared/components/modals/EditUserDeviceModal/EditUserDeviceModal.tsx b/web/src/shared/components/modals/EditUserDeviceModal/EditUserDeviceModal.tsx
index 94e1fe9901..2b475e98ec 100644
--- a/web/src/shared/components/modals/EditUserDeviceModal/EditUserDeviceModal.tsx
+++ b/web/src/shared/components/modals/EditUserDeviceModal/EditUserDeviceModal.tsx
@@ -53,7 +53,7 @@ export const EditUserDeviceModal = () => {
   );
 };
 
-const getFormSchema = (names: string[]) =>
+const getFormSchema = (names: string[], pubkeys: string[]) =>
   z.object({
     name: z
       .string()
@@ -63,13 +63,23 @@ const getFormSchema = (names: string[]) =>
     publicKey: z
       .string()
       .length(44, m.form_error_invalid())
-      .regex(patternValidWireguardKey, m.form_error_invalid()),
+      .regex(patternValidWireguardKey, m.form_error_invalid())
+      .refine((val) => !pubkeys.includes(val), m.form_error_key_exists()),
   });
 
-const ModalContent = ({ device, reservedNames, username }: OpenEditDeviceModal) => {
+const ModalContent = ({
+  device,
+  reservedNames,
+  reservedPubkeys,
+  username,
+}: OpenEditDeviceModal) => {
   const formSchema = useMemo(
-    () => getFormSchema(reservedNames.filter((name) => name !== device.name)),
-    [reservedNames, device.name],
+    () =>
+      getFormSchema(
+        reservedNames.filter((name) => name !== device.name),
+        reservedPubkeys.filter((key) => key !== device.wireguard_pubkey),
+      ),
+    [reservedNames, reservedPubkeys, device.name, device.wireguard_pubkey],
   );
 
   const { mutateAsync } = useMutation({
diff --git a/web/src/shared/hooks/modalControls/types.ts b/web/src/shared/hooks/modalControls/types.ts
index beadff12f5..cf9f1f860d 100644
--- a/web/src/shared/hooks/modalControls/types.ts
+++ b/web/src/shared/hooks/modalControls/types.ts
@@ -32,6 +32,7 @@ export interface OpenConfirmActionModal {
 export interface OpenEditDeviceModal {
   device: Device;
   reservedNames: string[];
+  reservedPubkeys: string[];
   username: string;
 }
 
@@ -39,6 +40,7 @@ export interface OpenAuthKeyRenameModal {
   id: number;
   name: string;
   username: string;
+  reservedNames: string[];
 }
 
 export interface OpenAddApiTokenModal {