# Additional UDP Port Setting

Source: https://forum.modalai.com/topic/5262/additional-udp-port-setting
Category: General Questions (https://forum.modalai.com/category/2/general-questions)
Posted: 2026-06-15 04:59:42 UTC by voxltester
Replies: 8 · Views: 3964

## voxltester · 2026-06-15 04:59:42 UTC

Hi,
I would like to have one more additional port to communicate VOXL2 from my laptop.
This is the current `voxl-mavlink-server.conf`
```
{
	"primary_static_gcs_ip":	"10.223.0.4",
	"primary_static_gcs_ip_port":	14550,
	"secondary_static_gcs_ip":	"10.223.0.4",
	"secondary_static_gcs_ip_port":	14600,
	"onboard_port_to_autopilot":	14556,
	"onboard_port_from_autopilot":	14557,
	"gcs_port_to_autopilot":	14558,
	"gcs_port_from_autopilot":	14559,
	"en_external_uart_ap":	false,
	"autopilot_uart_bus":	1,
	"autopilot_uart_baudrate":	921600,
	"autopilot_mission_delay_start":	-1,
	"autopilot_mission_delay_sound":	false,
	"autopilot_mission_force_restart":	0,
	"autopilot_mission_notif_dur":	0.1,
	"en_external_ap_timesync":	1,
	"en_external_ap_heartbeat":	1,
	"udp_mtu":	512,
	"gcs_timeout_s":	4.5
}
```
I am using `14550` for QGC and `14600` for MAVROS.
Is it possible to have one more UDP port for MAVSDK? I would like to run mavsdk from my laptop by running `await drone.connect(system_address="udp://:14xxx")`

Please let me know.
I would like to know if the following explanation is true;
`Up to 16 simultaneous external UDP connections can be established with voxl-mavlink-server. These can be connections to qGroundControl, MAVROS, MAVSDK, or any custom software on the same network as VOXL. `
in https://docs.modalai.com/mavlink/#mavlink-routing-on-voxl

## Reply by Eric Katzfey (ModalAI staff) · 2026-06-15 15:19:23 UTC

@voxltester The primary and secondary ip / port configurations are for destinations. voxl-mavlink-server will initiate connections to those. For incoming connections just send to port 14550. voxl-mavlink-server is listening on that port. When an incoming message from a new ip / port combo comes in it will store that and consider that a new connection. If you use drone.connect it is waiting for voxl-mavlink-server to connect to it rather than attempting to connect to voxl-mavlink-server on it's own.

## Reply by voxltester · 2026-06-17 04:19:07 UTC (in reply to Eric Katzfey)

@Eric-Katzfey 
Thank you for your answer.
In my setup, is it possible to have one more UDP port for MAVSDK?
How can I have an additional simultaneous external UDP connection?

## Reply by Eric Katzfey (ModalAI staff) · 2026-06-17 13:49:44 UTC (in reply to voxltester)

@voxltester That's what I just explained. Rather than initiate the connection from voxl-mavlink-server initiate it from MAVSDK.

## Reply by voxltester · 2026-06-17 14:43:01 UTC (in reply to Eric Katzfey)

@Eric-Katzfey 
Then which port should I use for it in my case?

## Reply by Eric Katzfey (ModalAI staff) · 2026-06-17 15:27:42 UTC (in reply to voxltester)

@voxltester Use any port you like. When you connect to voxl-mavlink-server at port 14550 it will remember the ip and port you connected from and maintain a connection with it.

## Reply by voxltester · 2026-06-23 06:04:50 UTC (in reply to Eric Katzfey)

@Eric-Katzfey I do not understand.
With the same port number, which is used by QGC, mavsdk shows an error that

```
bind error: Address not available (udp_connection.cpp:93)
Connection failed: Bind error (connection_initiator.h:47)
```

FYI, I ran 
```
    await drone.connect(
        system_address="udp://0.0.0.0:14550"
    )
```

## Reply by Eric Katzfey (ModalAI staff) · 2026-06-23 14:59:46 UTC (in reply to voxltester)

@voxltester You cannot use a port number that is already in use by another application. So pick a different one.

## Reply by Eric Katzfey (ModalAI staff) · 2026-06-23 15:01:48 UTC (in reply to voxltester)

@voxltester As I tried to explain before, don't wait for voxl-mavlink-server to connect to your application. You need to have it initiate the connection to voxl-mavlink-server.