Arris surfboard SBG8300 won't stay online

I have an Arris surfboard SBG8300, I have been using it for a year and I have had no issues with connecting to the internet. The apartment I was in had built in ethernet cable so I did not need the one provided by Xfinity. I recently moved to a new apartment and now have to use the Xfinity provided ethernet cable. The modem is working properly, the green wifi light is solid but the online blue light is blinking. The internet name is popping up but I have no solid connection. I chatted with customer service but was given no useful advice.