diff --git a/changelog.md b/changelog.md
index db580c8..fa2cc52 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,20 @@
 # Changelog
 
+## 2025-05-14 - 16.0.4 - fix(smartproxy)
+Update dynamic port mapping to support 'preserve' target port value
+
+- Refactored NetworkProxy to use a default port for 'preserve' values, correctly falling back to the incoming port when target.port is set to 'preserve'.
+- Updated RequestHandler and WebSocketHandler to check for 'preserve' target port instead of legacy preservePort flag.
+- Modified IRouteTarget type definitions to allow 'preserve' as a valid target port value.
+
+## 2025-05-14 - 16.0.4 - fix(smartproxy)
+Fix dynamic port mapping: update target port resolution to properly handle 'preserve' values across route configurations. Now, when a route's target port is set to 'preserve', the incoming port is used consistently in NetworkProxy, RequestHandler, WebSocketHandler, and RouteConnectionHandler. Also update type definitions in IRouteTarget to support 'preserve'.
+
+- Refactored port resolution in NetworkProxy to use a default port for 'preserve' and then correctly fall back to the incoming port when 'preserve' is specified.
+- Updated RequestHandler and WebSocketHandler to check if target.port equals 'preserve' instead of using a legacy 'preservePort' flag.
+- Modified RouteConnectionHandler to correctly resolve dynamic port mappings with 'preserve'.
+- Updated route type definitions to allow 'preserve' as a valid target port value.
+
 ## 2025-05-14 - 16.0.3 - fix(network-proxy, route-utils, route-manager)
 Normalize IPv6-mapped IPv4 addresses in IP matching functions and remove deprecated legacy configuration methods in NetworkProxy. Update route-utils and route-manager to compare both canonical and IPv6-mapped IP forms, adjust tests accordingly, and clean up legacy exports.
 
diff --git a/docs/porthandling.md b/docs/porthandling.md
new file mode 100644
index 0000000..e01dbee
--- /dev/null
+++ b/docs/porthandling.md
@@ -0,0 +1,468 @@
+# SmartProxy Port Handling
+
+This document covers all the port handling capabilities in SmartProxy, including port range specification, dynamic port mapping, and runtime port management.
+
+## Port Range Syntax
+
+SmartProxy offers flexible port range specification through the `TPortRange` type, which can be defined in three different ways:
+
+### 1. Single Port
+
+```typescript
+// Match a single port
+{
+  match: {
+    ports: 443
+  }
+}
+```
+
+### 2. Array of Specific Ports
+
+```typescript
+// Match multiple specific ports
+{
+  match: {
+    ports: [80, 443, 8080]
+  }
+}
+```
+
+### 3. Port Range
+
+```typescript
+// Match a range of ports
+{
+  match: {
+    ports: [{ from: 8000, to: 8100 }]
+  }
+}
+```
+
+### 4. Mixed Port Specifications
+
+You can combine different port specification methods in a single rule:
+
+```typescript
+// Match both specific ports and port ranges
+{
+  match: {
+    ports: [80, 443, { from: 8000, to: 8100 }]
+  }
+}
+```
+
+## Port Forwarding Options
+
+SmartProxy offers several ways to handle port forwarding from source to target:
+
+### 1. Static Port Forwarding
+
+Forward to a fixed target port:
+
+```typescript
+{
+  action: {
+    type: 'forward',
+    target: {
+      host: 'backend.example.com',
+      port: 8080
+    }
+  }
+}
+```
+
+### 2. Preserve Source Port
+
+Forward to the same port on the target:
+
+```typescript
+{
+  action: {
+    type: 'forward',
+    target: {
+      host: 'backend.example.com',
+      port: 'preserve'
+    }
+  }
+}
+```
+
+### 3. Dynamic Port Mapping
+
+Use a function to determine the target port based on connection context:
+
+```typescript
+{
+  action: {
+    type: 'forward',
+    target: {
+      host: 'backend.example.com',
+      port: (context) => {
+        // Calculate port based on request details
+        return 8000 + (context.port % 100);
+      }
+    }
+  }
+}
+```
+
+## Port Selection Context
+
+When using dynamic port mapping functions, you have access to a rich context object that provides details about the connection:
+
+```typescript
+interface IRouteContext {
+  // Connection information
+  port: number;          // The matched incoming port
+  domain?: string;       // The domain from SNI or Host header
+  clientIp: string;      // The client's IP address
+  serverIp: string;      // The server's IP address
+  path?: string;         // URL path (for HTTP connections)
+  query?: string;        // Query string (for HTTP connections)
+  headers?: Record<string, string>; // HTTP headers (for HTTP connections)
+
+  // TLS information
+  isTls: boolean;        // Whether the connection is TLS
+  tlsVersion?: string;   // TLS version if applicable
+
+  // Route information
+  routeName?: string;    // The name of the matched route
+  routeId?: string;      // The ID of the matched route
+
+  // Additional properties
+  timestamp: number;     // The request timestamp
+  connectionId: string;  // Unique connection identifier
+}
+```
+
+## Common Port Mapping Patterns
+
+### 1. Port Offset Mapping
+
+Forward traffic to target ports with a fixed offset:
+
+```typescript
+{
+  action: {
+    type: 'forward',
+    target: {
+      host: 'backend.example.com',
+      port: (context) => context.port + 1000
+    }
+  }
+}
+```
+
+### 2. Domain-Based Port Mapping
+
+Forward to different backend ports based on the domain:
+
+```typescript
+{
+  action: {
+    type: 'forward',
+    target: {
+      host: 'backend.example.com',
+      port: (context) => {
+        switch (context.domain) {
+          case 'api.example.com': return 8001;
+          case 'admin.example.com': return 8002;
+          case 'staging.example.com': return 8003;
+          default: return 8000;
+        }
+      }
+    }
+  }
+}
+```
+
+### 3. Load Balancing with Hash-Based Distribution
+
+Distribute connections across a port range using a deterministic hash function:
+
+```typescript
+{
+  action: {
+    type: 'forward',
+    target: {
+      host: 'backend.example.com',
+      port: (context) => {
+        // Simple hash function to ensure consistent mapping
+        const hostname = context.domain || '';
+        const hash = hostname.split('').reduce((a, b) => a + b.charCodeAt(0), 0);
+        return 8000 + (hash % 10); // Map to ports 8000-8009
+      }
+    }
+  }
+}
+```
+
+## IPv6-Mapped IPv4 Compatibility
+
+SmartProxy automatically handles IPv6-mapped IPv4 addresses for optimal compatibility. When a connection from an IPv4 address (e.g., `192.168.1.1`) arrives as an IPv6-mapped address (`::ffff:192.168.1.1`), the system normalizes these addresses for consistent matching.
+
+This is particularly important when:
+
+1. Matching client IP restrictions in route configurations
+2. Preserving source IP for outgoing connections
+3. Tracking connections and rate limits
+
+No special configuration is needed - the system handles this normalization automatically.
+
+## Dynamic Port Management
+
+SmartProxy allows for runtime port configuration changes without requiring a restart.
+
+### Adding and Removing Ports
+
+```typescript
+// Get the SmartProxy instance
+const proxy = new SmartProxy({ /* config */ });
+
+// Add a new listening port
+await proxy.addListeningPort(8081);
+
+// Remove a listening port
+await proxy.removeListeningPort(8082);
+```
+
+### Runtime Route Updates
+
+```typescript
+// Get current routes
+const currentRoutes = proxy.getRoutes();
+
+// Add new route for the new port
+const newRoute = {
+  name: 'New Dynamic Route',
+  match: {
+    ports: 8081,
+    domains: ['dynamic.example.com']
+  },
+  action: {
+    type: 'forward',
+    target: {
+      host: 'backend.example.com',
+      port: 9000
+    }
+  }
+};
+
+// Update the route configuration
+await proxy.updateRoutes([...currentRoutes, newRoute]);
+
+// Remove routes for a specific port
+const routesWithout8082 = currentRoutes.filter(route => {
+  const ports = proxy.routeManager.expandPortRange(route.match.ports);
+  return !ports.includes(8082);
+});
+await proxy.updateRoutes(routesWithout8082);
+```
+
+## Performance Considerations
+
+### Port Range Expansion
+
+When using large port ranges, SmartProxy uses internal caching to optimize performance. For example, a range like `{ from: 1000, to: 2000 }` is expanded only once and then cached for future use.
+
+### Port Range Validation
+
+The system automatically validates port ranges to ensure:
+
+1. Port numbers are within the valid range (1-65535)
+2. The "from" value is not greater than the "to" value in range specifications
+3. Port ranges do not contain duplicate entries
+
+Invalid port ranges will be logged as warnings and skipped during configuration.
+
+## Configuration Recipes
+
+### Global Port Range
+
+Listen on a large range of ports and forward to the same ports on a backend:
+
+```typescript
+{
+  name: 'Global port range forwarding',
+  match: {
+    ports: [{ from: 8000, to: 9000 }]
+  },
+  action: {
+    type: 'forward',
+    target: {
+      host: 'backend.example.com',
+      port: 'preserve'
+    }
+  }
+}
+```
+
+### Domain-Specific Port Ranges
+
+Different port ranges for different domain groups:
+
+```typescript
+[
+  {
+    name: 'API port range',
+    match: {
+      ports: [{ from: 8000, to: 8099 }]
+    },
+    action: {
+      type: 'forward',
+      target: {
+        host: 'api.backend.example.com',
+        port: 'preserve'
+      }
+    }
+  },
+  {
+    name: 'Admin port range',
+    match: {
+      ports: [{ from: 9000, to: 9099 }]
+    },
+    action: {
+      type: 'forward',
+      target: {
+        host: 'admin.backend.example.com',
+        port: 'preserve'
+      }
+    }
+  }
+]
+```
+
+### Mixed Internal/External Port Forwarding
+
+Forward specific high-numbered ports to standard ports on internal servers:
+
+```typescript
+[
+  {
+    name: 'Web server forwarding',
+    match: {
+      ports: [8080, 8443]
+    },
+    action: {
+      type: 'forward',
+      target: {
+        host: 'web.internal',
+        port: (context) => context.port === 8080 ? 80 : 443
+      }
+    }
+  },
+  {
+    name: 'Database forwarding',
+    match: {
+      ports: [15432]
+    },
+    action: {
+      type: 'forward',
+      target: {
+        host: 'db.internal',
+        port: 5432
+      }
+    }
+  }
+]
+```
+
+## Debugging Port Configurations
+
+When troubleshooting port forwarding issues, enable detailed logging:
+
+```typescript
+const proxy = new SmartProxy({
+  routes: [ /* your routes */ ],
+  enableDetailedLogging: true
+});
+```
+
+This will log:
+- Port configuration during startup
+- Port matching decisions during routing
+- Dynamic port function results
+- Connection details including source and target ports
+
+## Port Security Considerations
+
+### Restricting Ports
+
+For security, you may want to restrict which ports can be accessed by specific clients:
+
+```typescript
+{
+  name: 'Restricted port range',
+  match: {
+    ports: [{ from: 8000, to: 9000 }],
+    clientIp: ['10.0.0.0/8'] // Only internal network can access these ports
+  },
+  action: {
+    type: 'forward',
+    target: {
+      host: 'internal.example.com',
+      port: 'preserve'
+    }
+  }
+}
+```
+
+### Rate Limiting by Port
+
+Apply different rate limits for different port ranges:
+
+```typescript
+{
+  name: 'API ports with rate limiting',
+  match: {
+    ports: [{ from: 8000, to: 8100 }]
+  },
+  action: {
+    type: 'forward',
+    target: {
+      host: 'api.example.com',
+      port: 'preserve'
+    },
+    security: {
+      rateLimit: {
+        enabled: true,
+        maxRequests: 100,
+        window: 60 // 60 seconds
+      }
+    }
+  }
+}
+```
+
+## Best Practices
+
+1. **Use Specific Port Ranges**: Instead of large ranges (e.g., 1-65535), use specific ranges for specific purposes
+
+2. **Prioritize Routes**: When multiple routes could match, use the `priority` field to ensure the most specific route is matched first
+
+3. **Name Your Routes**: Use descriptive names to make debugging easier, especially when using port ranges
+
+4. **Use Preserve Port Where Possible**: Using `port: 'preserve'` is more efficient and easier to maintain than creating multiple specific mappings
+
+5. **Limit Dynamic Port Functions**: While powerful, complex port functions can be harder to debug; prefer simple map or math-based functions
+
+6. **Use Port Variables**: For complex setups, define your port ranges as variables for easier maintenance:
+
+```typescript
+const API_PORTS = [{ from: 8000, to: 8099 }];
+const ADMIN_PORTS = [{ from: 9000, to: 9099 }];
+
+const routes = [
+  {
+    name: 'API Routes',
+    match: { ports: API_PORTS, /* ... */ },
+    // ...
+  },
+  {
+    name: 'Admin Routes',
+    match: { ports: ADMIN_PORTS, /* ... */ },
+    // ...
+  }
+];
+```
\ No newline at end of file
diff --git a/ts/00_commitinfo_data.ts b/ts/00_commitinfo_data.ts
index 538fb1b..1a41132 100644
--- a/ts/00_commitinfo_data.ts
+++ b/ts/00_commitinfo_data.ts
@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@push.rocks/smartproxy',
-  version: '16.0.3',
+  version: '16.0.4',
   description: 'A powerful proxy package with unified route-based configuration for high traffic management. Features include SSL/TLS support, flexible routing patterns, WebSocket handling, advanced security options, and automatic ACME certificate management.'
 }
diff --git a/ts/proxies/network-proxy/network-proxy.ts b/ts/proxies/network-proxy/network-proxy.ts
index b1178c5..c208ece 100644
--- a/ts/proxies/network-proxy/network-proxy.ts
+++ b/ts/proxies/network-proxy/network-proxy.ts
@@ -447,6 +447,8 @@ export class NetworkProxy implements IMetricsTracker {
 
     // Create legacy proxy configs for the router
     // This is only needed for backward compatibility with ProxyRouter
+    
+    const defaultPort = 443; // Default port for HTTPS when using 'preserve'
     // and will be removed in the future
     const legacyConfigs: IReverseProxyConfig[] = [];
 
@@ -472,7 +474,8 @@ export class NetworkProxy implements IMetricsTracker {
         ? route.action.target.host
         : [route.action.target.host];
 
-      const targetPort = route.action.target.port;
+      // Handle 'preserve' port value
+      const targetPort = route.action.target.port === 'preserve' ? defaultPort : route.action.target.port;
 
       // Get certificate information
       const certData = certificateUpdates.get(domain);
diff --git a/ts/proxies/network-proxy/request-handler.ts b/ts/proxies/network-proxy/request-handler.ts
index e75cb18..dcb5b36 100644
--- a/ts/proxies/network-proxy/request-handler.ts
+++ b/ts/proxies/network-proxy/request-handler.ts
@@ -540,7 +540,7 @@ export class RequestHandler {
             this.logger.debug(`Resolved function-based port to: ${resolvedPort}`);
           }
         } else {
-          targetPort = matchingRoute.action.target.port;
+          targetPort = matchingRoute.action.target.port === 'preserve' ? routeContext.port : matchingRoute.action.target.port as number;
         }
 
         // Select a single host if an array was provided
@@ -760,7 +760,7 @@ export class RequestHandler {
             this.logger.debug(`Resolved HTTP/2 function-based port to: ${resolvedPort}`);
           }
         } else {
-          targetPort = matchingRoute.action.target.port;
+          targetPort = matchingRoute.action.target.port === 'preserve' ? routeContext.port : matchingRoute.action.target.port as number;
         }
 
         // Select a single host if an array was provided
diff --git a/ts/proxies/network-proxy/websocket-handler.ts b/ts/proxies/network-proxy/websocket-handler.ts
index ab15cf9..077d262 100644
--- a/ts/proxies/network-proxy/websocket-handler.ts
+++ b/ts/proxies/network-proxy/websocket-handler.ts
@@ -204,7 +204,7 @@ export class WebSocketHandler {
             targetPort = route.action.target.port(toBaseContext(routeContext));
             this.logger.debug(`Resolved function-based port for WebSocket: ${targetPort}`);
           } else {
-            targetPort = route.action.target.port;
+            targetPort = route.action.target.port === 'preserve' ? routeContext.port : route.action.target.port as number;
           }
 
           // Select a single host if an array was provided
diff --git a/ts/proxies/smart-proxy/models/route-types.ts b/ts/proxies/smart-proxy/models/route-types.ts
index 495daa6..b32a150 100644
--- a/ts/proxies/smart-proxy/models/route-types.ts
+++ b/ts/proxies/smart-proxy/models/route-types.ts
@@ -69,8 +69,7 @@ export interface IRouteContext {
  */
 export interface IRouteTarget {
   host: string | string[] | ((context: IRouteContext) => string | string[]);  // Host or hosts with optional function for dynamic resolution
-  port: number | ((context: IRouteContext) => number);  // Port with optional function for dynamic mapping
-  preservePort?: boolean;   // Use incoming port as target port (ignored if port is a function)
+  port: number | 'preserve' | ((context: IRouteContext) => number);  // Port with optional function for dynamic mapping (use 'preserve' to keep the incoming port)
 }
 
 /**
diff --git a/ts/proxies/smart-proxy/route-connection-handler.ts b/ts/proxies/smart-proxy/route-connection-handler.ts
index c0cd4ee..8157af7 100644
--- a/ts/proxies/smart-proxy/route-connection-handler.ts
+++ b/ts/proxies/smart-proxy/route-connection-handler.ts
@@ -434,8 +434,8 @@ export class RouteConnectionHandler {
         this.connectionManager.cleanupConnection(record, 'port_mapping_error');
         return;
       }
-    } else if (action.target.preservePort) {
-      // Use incoming port if preservePort is true
+    } else if (action.target.port === 'preserve') {
+      // Use incoming port if port is 'preserve'
       targetPort = record.localPort;
     } else {
       // Use static port from configuration
@@ -525,7 +525,7 @@ export class RouteConnectionHandler {
       let targetPort: number;
       if (typeof action.target.port === 'function') {
         targetPort = action.target.port(routeContext);
-      } else if (action.target.preservePort) {
+      } else if (action.target.port === 'preserve') {
         targetPort = record.localPort;
       } else {
         targetPort = action.target.port;