Launch ´mtr google.com’ on one of your devices (preferably connected via Ethernet to your router) a few minutes before the cut off, and watch what happens when the cut occurs. It will show you exactly which equipment on the route starts dropping.
Although I suspect your ISP has a 24h lease and your modem renegociates at 3:40 everyday
Although I suspect your ISP has a 24h lease and your modem renegociates at 3:40 everyday