Hello @MaryDD
You should be able to use the Google Home app to see which devices are currently using the most internet capacity. To do that, launch the Google Home app, then tap the "Wifi" bubble at the top, then tap the "<#> devices> bubble (where "<#>" is the number of devices currently connected to your network). The next screen that comes up should be a list of currently-connected devices sorted by highest usage. It should update every 5 seconds, so watch it for long enough to get a feel for which devices are using the most capacity.
All of that said, a typical voice call doesn't use much capacity. A video call uses a bit more, but may not be significant. Streaming video uses more, but is bursty – large chunks of data get downloaded every few seconds with idle time in between. Analyzing network congestion issues can be extremely challenging, since there are so many different possible sources of issues. You could be sharing a busy WiFi channel with a neighbor, for example, which wouldn't show up in the Google Home app. Or, your internet service provider's connection could be congested by all of the traffic in your area (which also wouldn't show up in the app). So, it may be hard to know for sure – take what the app says as just one data point.
