Nighthawk RAX75, I have 1GB download speed at router but devices don't get more than ~125MB on 5Ghz

I have the RAX75 and I am having the SAME issues. I have a 1gb internet connection and it’s testing on the device Speedtest 975mb and 760mb upload. Max speedtest is 130mb on a 5gb connection. Then when I merge the 5 GHz and 2.4GHz Channels with smartconnect I seem to have issues with internet not connecting consistently on my phone apps. So I separated the channels, but on 5Ghz I’m still not able to download more than 130mb. With 2.4GHz it’s under 60mb and I’m 5’ from the wifi router