If you have a openwrt router than it should be quite simple. Redirect the traffic from the ip of the washing machine to a machine that has mitmproxy installed (

If you have a openwrt router than it should be quite simple. Redirect the traffic from the ip of the washing machine to a machine that has mitmproxy installed (using iptables). Hopefully the protocol is https and it doesn't have some form of certificate pinning. That should get you the raw requests/responses.