# Connection problems between URsim docker and ROS2 without the real robot

**URL:** <https://forum.universal-robots.com/t/connection-problems-between-ursim-docker-and-ros2-without-the-real-robot/31587>\
**Category:** ROS\
**Created:** [November 27, 2023, 8:10pm UTC](https://forum.universal-robots.com/t/connection-problems-between-ursim-docker-and-ros2-without-the-real-robot/31587 "2023-11-27T20:10:12Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![hernandez-w](https://avatars.discourse-cdn.com/v4/letter/h/a183cd/32.png) [@hernandez-w](https://forum.universal-robots.com/u/hernandez-w)\
**Post date:** [November 27, 2023, 8:10pm UTC](https://forum.universal-robots.com/t/connection-problems-between-ursim-docker-and-ros2-without-the-real-robot/31587/1 "2023-11-27T20:10:12Z")

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I’m trying to connect URSim to the external control without the actual robot. I use docker  
The process I’m running is:

- ros2 run ur\_client\_library start\_ursim.sh -m ur3
- Open docker htt://192.168.56.101:6080/vnc
- ros2 launch ur\_robot\_driver ur\_control.launch.py ur\_type:=ur3 robot\_ip:=192.168.56.101 launch\_rviz:=false use\_fake\_hardware:=true

when I try to connect from the URSim I get the error

- The conection to the remote PC at 192.168.56.1:50004 could not be estable. Reason: Conection refused

 ![image](https://us1.discourse-cdn.com/flex020/uploads/universal_robots/original/2X/a/a659c279eb45812b7851b6f54568880c745a5226.png)  
I am using virtuabox with ubuntu 22.04

thank you very much for the help

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**Author:** ![colinchan986](https://avatars.discourse-cdn.com/v4/letter/c/5daacb/32.png) [@colinchan986](https://forum.universal-robots.com/u/colinchan986)\
**Post date:** [July 25, 2024, 10:25am UTC](https://forum.universal-robots.com/t/connection-problems-between-ursim-docker-and-ros2-without-the-real-robot/31587/2 "2024-07-25T10:25:27Z")

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i think you should launch the driver on the PC first, then press “play” button on the Polyscope.

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**Author:** ![cec.invre](https://avatars.discourse-cdn.com/v4/letter/c/34f0e0/32.png) [@cec.invre](https://forum.universal-robots.com/u/cec.invre)\
**Post date:** [March 20, 2025, 2:41pm UTC](https://forum.universal-robots.com/t/connection-problems-between-ursim-docker-and-ros2-without-the-real-robot/31587/3 "2025-03-20T14:41:33Z")

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I think it’s because you shouldn’t launch the robot with _use\_fake\_hardware_. the docker is already creating a fake simulation and URSim reads it as a real robot whereas if you run it with fake hardware it uses different settings. Correct command is:  
ros2 launch ur\_robot\_driver ur\_control.launch.py ur\_type:=ur3 robot\_ip:=192.168.56.101 launch\_rviz:=false