README states:

"Address to listen. Use '0.0.0.0' to listen to all available interfaces."

However, this value for "host" only listens on IPv4 addresses. A minimal program, such as this:
"""
from robotremoteserver import RobotRemoteServer as rs

class DummyClass ():
def init (self):
pass

rs (DummyClass (), host = "0.0.0.0")
"""

only listens on 0.0.0.0, which is an ipv4 address, rather than ::, which would include ipv4 and ipv6. The listening ports can be spotted, on linux, with netstat -anp |grep python, in a separate terminal, which produces something like this:
"""
tcp 0 0 0.0.0.0:8270 0.0.0.0:* LISTEN 10921/python3
"""