How to block device from accessing the internet.

I have a few smart home devices on my network that have way more traffic with the internet than they should. An example is a nearly 10 year old Yamaha receiver having hundreds of Megs of data transferred when the FW wasn't updated, and no online services are setup on it. Whats the easiest way to disconnect these devices from the internet, while still making them accessible from the LAN? I thought there used to be a checkbox under the client popout that had an option to the effect of "limit access to internet," but that was a few FW revs ago and I can't find anything like that.

To be clear I don't want to just limit overall bandwidth, because in the case of my receiver, I am still able to adjust all it's settings over the LAN through home assistant.

My home network is an ER605V2, an OC300, 2 SG2210P POE switches, and a few wireless APs. Any help or direction is greatly appreciated.