# Change px4 sitl gazebo ports for gcs and API

**URL:** <https://discuss.px4.io/t/change-px4-sitl-gazebo-ports-for-gcs-and-api/47399>\
**Category:** MAVLink\
**Created:** [September 14, 2025, 9:05am UTC](https://discuss.px4.io/t/change-px4-sitl-gazebo-ports-for-gcs-and-api/47399 "2025-09-14T09:05:44Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Pushkar\_Prasad](https://discuss.px4.io/user_avatar/discuss.px4.io/pushkar_prasad/32/20316_2.png) [@Pushkar\_Prasad](https://discuss.px4.io/u/Pushkar_Prasad)\
**Post date:** [September 14, 2025, 9:05am UTC](https://discuss.px4.io/t/change-px4-sitl-gazebo-ports-for-gcs-and-api/47399/1 "2025-09-14T09:05:44Z")

</div>

I want to run two commands like these back to back

```auto
make px4_sitl gazebo_plane 
make px4_sitl gazebo_standard_vtol

```

The idea is to eventially have them work on following

Plane: 14550 (GCS), 14540 (API)  
VTOL : 14552 (GCS), 14541(API)

so that at the same time, I can connect them to GCS, and be able to programatically connect them via mavsdk-python code and control them via code. They both need to work together, which is why I want them to be simulated together, and have to be on same GCS.

How do I accomplish this? I’m using ubuntu btw.

---

<div class="post-metadata">

**Author:** ![JulianOes](https://discuss.px4.io/user_avatar/discuss.px4.io/julianoes/32/30_2.png) [@JulianOes](https://discuss.px4.io/u/JulianOes)\
**Post date:** [September 14, 2025, 10:00pm UTC](https://discuss.px4.io/t/change-px4-sitl-gazebo-ports-for-gcs-and-api/47399/2 "2025-09-14T22:00:43Z")

</div>

You need to start it with different instances.

For old/classic Gazebo there is a script:

> **[Multi-Vehicle Simulation with Gazebo Classic | PX4 Guide (main)](https://docs.px4.io/main/en/sim_gazebo_classic/multi_vehicle_simulation.html)**
>
> PX4 User and Developer Guide

With new Gazebo (Gz) it’s easier and you can just start individual instances using the instance argument:

> **[Multi-Vehicle Simulation with Gazebo | PX4 Guide (main)](https://docs.px4.io/main/en/sim_gazebo_gz/multi_vehicle_simulation.html)**
>
> PX4 User and Developer Guide