gaierror: [Errno -5] when using SSHLibrary

Question

I am running robotframework inside a Docker container. When I ssh to srv1 from the CLI of the container it works, but when I run the following robotframework test script, I get gaierror: [Errno -5] No address associated with hostname. Does anyone know why I am getting this error?

# robot sshtest.robot
==============================================================================
Sshtest
==============================================================================
Connecting to another machine                                         | FAIL |
gaierror: [Errno -5] No address associated with hostname
------------------------------------------------------------------------------
Sshtest                                                               | FAIL |
1 test, 0 passed, 1 failed
==============================================================================

This is the robotframework test script.

*** Settings ***
Library     SSHLibrary


*** Variables ***
${REMOTEIP}     srv1
${USERNAME}     admin
${PASSWORD}     admin@123


*** Test Cases ***
Connecting to another machine
    Open Connection    host=${REMOTEIP}
    Login    username=${USERNAME}    password=${PASSWORD}