Receiving robot inactive alarm
If you are able to telnet the robot ip address on port 48000 and also able to telnet from robot to hub on port 48002 but still receive the alarm.
Ccheck the controller logs and look for this type message
Controller: failed to send alive to hub UIMMON7hub(10.1.1.61) - communication error
But no firewall between Robot and Hub you can open the wireshark if windows or do a TCP dump at Linux to check the request from hub to robot and see the results if the robot don't reply the hub request.