What to do when suspicious device detected on network

Last night an Avast Premium Security scan detected a new device on my network. It’s an “unknown device” but the brand is Arcadyan, which I found makes routers. I have added nothing to my network and my current Arris router and D-Link booster still show up. I don’t have any Amazon devices (like Alexa or Ring) so I don’t think it’s part of Amazon’s new “feature.” So, I’m concerned, but have no idea what I can do about it. I welcome suggestions.
It’s interesting to know from the Avast product that there’s an intruder on the network, but now I feel helpless!
Thank you.

Does this shed any light on your problem?
https://internet-access-guide.com/arcadyan-device-on-network/