Netgear model GS724TP

Okay so we purchased this switch to help with adding more IP phones to the network. This is for a business (doctor's office) and everything has been working great, except today! Out of no where the devices plugged into this switch stopped getting internet connections. After unplugging the switch and plugging it back in and letting it reboot everything started working back to normal again. Is there a reason this happened? As this is a doctor's office and we really can't have phones stop working, what can I do to prevent this from happening again?? Please help!!