@Nat10259 Does your ISP offer a mobile router like a NetGear Nighthawk? I live in an area that has limited service (DSL) and suffers power outages. With my Nighthawk, I am able to get connected and use my TV and computer along with a battery power source. I have it for travelling in my motor home to keep my phone connected, and again for accessing the internet while camping. If I were going to offer it to guests, I could expense it. Too late in this instance, but something to consider.
As to what to do for your current guests, a 50% discount is IMO, too much -- its not as if the bed was broken or the pool was polluted. They probably did fine with their phone service, eh? A gift card for a dinner out might do, or a 10% refund.