Hi @KelMurphy ! Thanks for connecting with the Shopify Community.
It’s hard to know exactly what is causing this issue without furthering investigation. I’ve opened your store using Safari, Chrome, and Firefox. I tried on 2 different laptops and my phone and all worked. Since you said the site worked for them once they turned off their Wifi connection, it leads me to believe it is an issue with their Internet provider, routers specifically, or DSL connection. I would ask them their service providers name to see if they match.
Do you also have the dates that this started happening? Is it still happening for them?