Interesting. Are you sure it's your internet connection, your modem/router or could it be the device you're using?
One way to isolate the cause is to try to reproduce this 1 minute interruption on more than 1 device. For example, watch YouTube on your laptop, as well as on your phone (using WiFi obviously), on your Chromecast and on your Firestick (for example).
If they all get cut 1 minute, then it maybe be your modem/router. If only one cuts, then it may be some configuration for that device.