Service keeps crashing? Green/yellow blinking lights?

I just moved and had to switch to Cox in my new apartment. Initially, the internet took a a little while to work but that's to be expected. For the past two days, however, the internet is either slow or crashing. I paid for 500mbps and see no outages. Light on my rented router keeps blinking either green, yellow or both when the internet goes out. This is after several hours of normal or spotty internet. I have to unplug for 15-30 min for my internet to work again. What the heck is going on? I'm a student and need internet desperately right now.