Check that your wifi has only the devices you own connected, could be someone guessed your wifi password and is taking your network for a ride.
Log into your routers web interface, and usually they have a list of connected clients or DHCP addresses, look for any devices that seem out of the ordinary. Some routers even have traffic analysers, and can point out where your usage is coming from.
My other go to would have been an Xbox, those chew data like crazy.
Other than that you could be victim to a breakin, and your data could be being copied elsewhere, or you could be part of one of those ISP wifi sharing things (Telstra in Australia did that) and have had the usage of other people counting on your usage.
Check that your wifi has only the devices you own connected, could be someone guessed your wifi password and is taking your network for a ride.
Log into your routers web interface, and usually they have a list of connected clients or DHCP addresses, look for any devices that seem out of the ordinary. Some routers even have traffic analysers, and can point out where your usage is coming from.
My other go to would have been an Xbox, those chew data like crazy.
Other than that you could be victim to a breakin, and your data could be being copied elsewhere, or you could be part of one of those ISP wifi sharing things (Telstra in Australia did that) and have had the usage of other people counting on your usage.