I have two IoTaWatts (iotawatt.com) for all the circuits in my home. I also use Z-Wave and Zigbee devices to monitor individual plugs (I love these). I send data from all of this to an InfluxDB database and then into Grafana for displaying pretty graphs. Everything is running on my Windows desktop. The IoTaWatt doesn’t require internet access to work. I have been very happy with the setup and once setup it hasn’t required much maintenance.
The system is also good for recording temperatures, solar power information, and anything else that can make an API call. Not sure why your Z-Wave is falling off the network, for that I use a Hubitat and mostly Inovelli, Zooz, and THIRDREALITY ZigBee plugs.