Duplicati problem "The connection to the server is lost"

Hi, I have successfully installed duplicati on OMV4, and can then access web interface ( listen address set to 0.0.0.0). have set up backups and is nicely backing up to amazon drive. However when I reset the machine and then try to access the web interface i get the message "the connection to the server is lost, attempting again in ... ". This loops indefinitely and is not fixed by a reboot.
Any idea how to fix this?

thanks macom, tried putting in the ip of the omv box but it still gives the same fault.
anyone else experienced this?