500mbps down 970 up? Gig line issues

For the past I have not been getting near the 1 gig down. Now before I get a generic response, I have been searching all over this form for answer and tried every thing. 

1: I have already ran the troubleshoot from Troubleshoot Internet

2. I have already hard reset my router.

3. I tried changing power outlets.

4. Reset the box the the fiber line connects too

5. no wires outside are broken

6: I have a cat 6 cable brand new, I even tried another cable three times, same issue. 

7. I have scanned for malware and ran a deep scan and the results were negative. 

8.

13. I've even tried full duplex, same issue

. I then used ipconfig /flushdns I even restarted my computer same issue

Furthermore. there are no active downloads, my CPU is fine, my ram is fine. I do not wish to have the response "maybe your hardware", when it is a gaming computer and it's been only a week. I called customer service issue not resolved. There are no errors related to affect my speed according to the event viewer. my cables are fine, and no point of a technician and charging me if according to others on here who's called them never got their issue resolved. 

So, what this tells me, it has to be an AT&T issue. Something on your end AT&T. 

Also the "speed test" built in the router I wouldn't trust those results. As far as I can see from researching this forum, its made to show everything is ok and to purposely report false positive speed test results. 

I have tested with another computer wired and that also has the correct specs to handle GIG speeds and I get the same speeds. 

-I've already ran the PC maintenance box and it is very inaccurate. Again, this has been an issue for about a week.

-Also, I have changed the port of where my Ethernet cord comes in. Also, I am the only one wired, I have disabled  WiFi and I only gained 5mbps 

-I also had a VPN installed, I uninstalled same issue.

(Numerous speed test) 

So, what now??