fidium fiber XR1000

I have the XR1000 and just got Fidium Fiber about a month ago.  I have the 1 Gig plan.  I have been doing a lot of testing with speeds.  We are a streaming houshold with multiple gaming consoles and primarily steam our media, Youtube Tv, Netflix and so on.  I am not getting the speeds I thought I would consistently.  My average speeds are between 500-600 for download and upload.  I know I'm not going to get the 1Gig but I was hoping to see my speeds in the 800-900 consistently.  I have had some buffering issues with our steaming apps didn't really have any issue before with Xfinity.  My question is are there any settings I need to change in my router settings that could help with this.  I have left them as they were when I had Xfinity.  I did call Fidium when they set up my service and had them add my router the xr1000. They just needed my MAC address and was able to use my router and disconnect theirs.Any help would be much appreciated.  My next step would be to disconnect the XR1000 and set up their wifi router and test it for a week or so.  I really love this router for the gaming options it has and woud hate to have to swtich