The following pipeline script (using docker-flow-plugin v1.7):

node {
    docker.withServer('tcp://1.2.3.4:2375').image('hello-world').inside {
        stage 'Docker'
    }
}

raises a RejectedAccessException (see error.txt for full log).

Using the withServer function in the docker-workflow-plugin demo project, I adjusted in "flow.groovy":

def maven = docker.withServer('tcp://1.2.3.4:2375').image('maven:3.3.9-jdk-8');

The solution mentioned in JENKINS-30414: restarting after install due to script-security, doesn't help.