Yes. I understand that the “nut server” is physically connected to the ups, but how does the “client” communicate to the server? I see the username and password but I don’t see an address connection.
OMV can not host a NUT server, it can only connect to a UPS via USB directly to OMV or as a netclient. To be able to use netclient you need to have a NUT in a container and configured as a netserver. there you can connect all of the UPS via USB and assign names to each one of the UPS and create users in the NUT netserver. once is configured you can set the netclient in OMV with the IP:port(NUT Port) and user/pass you created in the netserver. also you need to fill the UPS name with the name (you need to create a setting per UPS in NUT and name each UPS) of the UPS you want to monitor from the netserver in your OMV UPS configuration.
Example:
I have a NUT netserver configured in my HA with the UPS connected via USB to HA server. My OMV server power plug is connected to the same UPS as HA. My OMV server is in another location running headless and the UPS addon running as netclient connected to my NUT netserver in HA in a gigabit network.
