My Arris DG1670A wireless modem/router is effectively a lag switch.

My Arris DG1670A wireless modem/router's wifi cuts out about every 30s to 1min then instantly comes back on. I'm not getting the same problem when plugged in to the ethernet. Router was broadcasting 2 different channels and I switched the unused one off but it hasn't helped much. I don't know that much about network configuration and I just moved locations requiring a new service provider (Grande) who's customer service is terrible so some input would be greatly appreciated.