Nothing mentioned in this thread was wrong. The misidentification is unrelated to the 3.6GiB.

As this post has been incorrectly reported: Just to clarify the data usage is correctly attributed to the IP address used by the LG Washing Machine. I am monitoring the data usage more closely.

What I was referencing in inaccuracy of the router is the attribution of 622 bytes to Apple iMessage. The rogue process is likely using the same port (5223) as iMessage and ASUS router is wrongly attributing it to that.