diff --git a/app/Http/Controllers/Admin/ServersController.php b/app/Http/Controllers/Admin/ServersController.php
index 1805a831a3..2011d19485 100644
--- a/app/Http/Controllers/Admin/ServersController.php
+++ b/app/Http/Controllers/Admin/ServersController.php
@@ -66,12 +66,30 @@ public function __construct(
      *
      * @throws DataValidationException
      * @throws \Pterodactyl\Exceptions\Repository\RecordNotFoundException
+     * @throws ValidationException
      */
     public function setDetails(Request $request, Server $server): RedirectResponse
     {
-        $this->detailsModificationService->handle($server, $request->only([
-            'owner_id', 'external_id', 'name', 'description',
-        ]));
+        if ($request->input('external_id')) {
+            $externalId = $request->input('external_id');
+            $exists = Server::where('external_id', $externalId)
+                ->where('id', '!=', $server->id)
+                ->exists();
+
+            if ($exists) {
+                throw ValidationException::withMessages([
+                    'external_id' => 'The external identifier must be unique among all servers.',
+                ]);
+            }
+        }
+
+        try {
+            $this->detailsModificationService->handle($server, $request->only([
+                'owner_id', 'external_id', 'name', 'description',
+            ]));
+        } catch (DataValidationException $exception) {
+            throw new ValidationException($exception->getValidator());
+        }
 
         $this->alert->success(trans('admin/server.alerts.details_updated'))->flash();
 
diff --git a/app/Http/Requests/Admin/ServerFormRequest.php b/app/Http/Requests/Admin/ServerFormRequest.php
index bf461dc956..08e5d56b15 100644
--- a/app/Http/Requests/Admin/ServerFormRequest.php
+++ b/app/Http/Requests/Admin/ServerFormRequest.php
@@ -53,6 +53,21 @@ public function withValidator(Validator $validator): void
             ], function ($input) {
                 return !$input->auto_deploy;
             });
+
+            if ($this->input('external_id')) {
+                $server = $this->route('server');
+                $externalId = $this->input('external_id');
+
+                $query = Server::where('external_id', $externalId);
+
+                if ($server) {
+                    $query->where('id', '!=', $server->id);
+                }
+
+                if ($query->exists()) {
+                    $validator->errors()->add('external_id', 'The external identifier must be unique among all servers.');
+                }
+            }
         });
     }
 }
diff --git a/app/Models/Server.php b/app/Models/Server.php
index 0350fdf3f1..effa8f6b97 100644
--- a/app/Models/Server.php
+++ b/app/Models/Server.php
@@ -12,6 +12,7 @@
 use Illuminate\Database\Eloquent\Relations\MorphToMany;
 use Illuminate\Database\Eloquent\Relations\HasManyThrough;
 use Pterodactyl\Exceptions\Http\Server\ServerStateConflictException;
+use Illuminate\Validation\Rule;
 
 /**
  * \Pterodactyl\Models\Server.
@@ -217,6 +218,35 @@ public function isSuspended(): bool
         return $this->status === self::STATUS_SUSPENDED;
     }
 
+    public static function getRulesForUpdate($model, string $column = 'id'): array
+    {
+        if ($model instanceof Model) {
+            [$id, $column] = [$model->getKey(), $model->getKeyName()];
+        }
+
+        $rules = static::getRules();
+        foreach ($rules as $key => &$data) {
+            foreach ($data as &$datum) {
+                if (!is_string($datum) || !str_starts_with($datum, 'unique')) {
+                    continue;
+                }
+
+                [, $args] = explode(':', $datum);
+                $args = explode(',', $args);
+
+                if ($key === 'external_id') {
+                    $datum = Rule::unique($args[0], $args[1] ?? $key)
+                        ->ignore($id ?? $model, $column)
+                        ->whereNotNull('external_id');
+                } else {
+                    $datum = Rule::unique($args[0], $args[1] ?? $key)->ignore($id ?? $model, $column);
+                }
+            }
+        }
+
+        return $rules;
+    }
+
     /**
      * Gets the user who owns the server.
      *