Got my IotaWatt working, but now

Can’t speak for all routers, but I can assign a fixed IP outside of the pool range with my Cisco router.

I also just do a network scan of my environment which gives up the MAC address as well. Many network scanning tools will even provide you a guess of the company the product is made from, or help you locate it by showing your other assets on the network. There are tools for your smartphone and computer alike.