Sudden Complete Internet Loss

So for the second time in the past 9 months, I had a complete and sudden internet loss that completely took down my entire organization's product for 20 minutes. We broadcast a live show 2-3 evenings a week so there are literally less than 10 hours a week we need to have solid, uninterrupted service, and for the most part our service has been good for the last two years. But this massive, complete, and sudden loss of all service would not be a problem at noon or 2pm or 9am, but when it happens during an event it has a massive negative impact on our customers and our revenue stream. 

Rebooting the modem (twice, once with just me power-cycling and once with the automated tech support line doing it) and then waiting another frantic 5 minutes while I tried to reach ANYONE at customer service finally got me back online, but 20 minutes of downtime in a 3-hour event is A LOT. 

Should I be power-cycling the modem once a week or something to prevent this? Is there something I can do? Some sort of setting to signal when our most important times are? How do I prevent this from happening again? I'm fine with occasional signal outages but I need them to not happen in the 5pm-9:30pm pacific time window on Monday, Wednesday, or Thursday. Help!