Everything set up great.

My internet is 800Mbps.

Then I ran a speed test on my non-extended network 5Ghz and the speed were about 710Mbps.

The extender placement was shown to be great.

Upon connecting to my 5Ghz-Ext connection and running the same test, my speeds were 260Mbps.
I checked every setting I could find on the extender and I cannot figure out the issue.
Why is it almost 1/3 the speed of what I get on my regular 5Ghz network?