Gigablast barely reaching 550mbps after multiple tech support appointments and several different answers

Thanks for the replies, I had another tech that came out, he couldn't solve the issue and was never able to get a speed test over 600mbps, his test device showed 1.2gbps so he tried to tell me it was my devices which was false.  So when he connected his own laptop directly to the modem and then modem though router, the speed test showed the same 400-500mbps and that's using CAT6...one of the things we discovered is when using multiple speed test websites, once at a time, the closest Cox server in my county has an issue and always runs 200-500mbps, I tried other non-cox servers and was able to get 600-700mbps, but still not constantly, so he left confused with the problem unresolved just like the others.  

After he left I figured out the solution on my own..

#1. if you're using windows, you must download the speed-test application and never use the cox speed test or even the speed test.net internet page as they always show lower speeds.  Once I used the desktop speed test app my speeds shot up to 700-900mbps on non-cox servers in this area, so my speeds are better than I thought, the speed test websites and servers were showing slower speeds when using the web based test. So if you're in SoCal don't use the Cox servers for speed test right now and everyone else make sure you use the desktop speed test apps.

#2. I purchased some CAT7 cable just to see if it would make a difference... and boom, just like that speeds were testing from 900mbps to 1.3gbps.  So I replaced all the Cat6 and Cat5e cables with CAT7 and I now have the blazing speeds on wired connections and running about 600-700mbps wireless speeds.

Hope this helps someone else...  take care and thanks again for the replies