Unlikely to be caused by a cut cable, if it is affecting more than one of you in an area. More likely to be a problem at the exchange or local node if there is any fibre-optic in the local network (not to your house. This type of fault sometimes comes about when they are carrying out re-arrangements in the local exchange or node, and are usually completed with within a few hours (in the UK) and then the service comes back up again to normal, usually over some 5-12 hours.
Might be worth powering off your router for 5 minutes, and then powering it up again. If it hasn't come back up to normal after that I would report it.