Broadband goes out at the same time every night

This past summer the uverse broadband would go out for a few hours beginning at 8 pm. Coming back on at 10 pm. Then it wouldn’t come back on til midnight. Now it starts an hour earlier and doesn’t come back on until 4 am. We’ve had multiple technicians and three modem replacements. Nothing has worked. Haven’t even received a discount for lack of service.