Slow speed problems continue with g36 upgrade from CAX30

Over the past year, I have had continued slow download speeds (200-300 Mbps) on my Gigabit service.  I knew that my CAX30 was limited to 949 Mbps, so I upgrade to an Arris G36 per recommendations on this site.  My speeds continue to be just as low, no with noticeable impacts on browsing or streaming (buffer waits).  Wondering if this new modem was provisioned right, or if there is a local WAN problem?