ARRIS SBG10

I had internet up until yesterday. Then the 3rd light disappeared. I called Arris and they were unable to troubleshoot it. I went and bought another  brand new Arris modem/router and all lights show up but xfinity app unable to find my modem.  I called Tech Support she said she sent a signal to my modem and nothing. I swapped out the cable connections tried even a different spot on my apartment. Neither one of the Arris modems will connect. All lights on but no internet. Anyone out there able to help? Technician is coming out in 2 days and that's a long time for me to be down. Out of the blue my internet just quit working after working fine for months.