Unable to connect to IB using the Docker Toolbox tutorial

When trying to connect to Interactive Brokers using the Docker Toolbox tutorial, I get the error message given at the bottom of this post. I checked the forums for similar posts and tried:

docker exec quantrocket_ibg1_1 env

I confirmed the TWS password and User ID were correct and that this account is a paper trading account and is listed as paper trading in the configuration wizard.

Any tips on how to troubleshoot the problem would be much appreciated.

$ quantrocket launchpad start --wait

ibg1:
error: "gateway still not running after a reasonable wait: \nIBController is running
\ but IB Gateway is not accepting connections. IBController log output is below:\n
Exception in thread "main" java.awt.AWTError: Can't connect to X11 window server
\ using ':0' as the value of the DISPLAY variable.\n\tat sun.awt.X11GraphicsEnvironment.initDisplay(Native
\ Method)\n\tat sun.awt.X11GraphicsEnvironment.access$200(X11GraphicsEnvironment.java:65)\n
\tat sun.awt.X11GraphicsEnvironment$1.run(X11GraphicsEnvironment.java:115)\n\t
at java.security.AccessController.doPrivileged(Native Method)\n\tat sun.awt.X11GraphicsEnvironment.(X11GraphicsEnvironment.java:74)\n
\tat java.lang.Class.forName0(Native Method)\n\tat java.lang.Class.forName(Class.java:264)\n
\tat java.awt.GraphicsEnvironment.createGE(GraphicsEnvironment.java:103)\n\tat
\ java.awt.GraphicsEnvironment.getLocalGraphicsEnvironment(GraphicsEnvironment.java:82)\n
\tat sun.awt.X11.XToolkit.(XToolkit.java:126)\n\tat java.lang.Class.forName0(Native
\ Method)\n\tat java.lang.Class.forName(Class.java:264)\n\tat java.awt.Toolkit$2.run(Toolkit.java:860)\n
\tat java.awt.Toolkit$2.run(Toolkit.java:855)\n\tat java.security.AccessController.doPrivileged(Native
\ Method)\n\tat java.awt.Toolkit.getDefaultToolkit(Toolkit.java:854)\n\tat ibcontroller.IBController.createToolkitListener(Unknown
\ Source)\n\tat ibcontroller.IBController.load(Unknown Source)\n\tat ibcontroller.IBGatewayController.main(Unknown
\ Source)"
status: error

Is this error repeatable if you stop and restart the IB Gateway:

quantrocket launchpad stop --wait 
quantrocket launchpad start --wait

Is it repeatable if you recreate the container?

docker-compose -p quantrocket up -d --force-recreate ibg1

this still happens to me and the suggested solutions (stop/start/recreate) did not help

ok, resolved for me. you cannot start the ibg without an active (paid) subscription.
you should mention that in the documentation, because people in the learning stage (like me) don't immediately pay for a service.