Nighthawk R7900P - slow internet speeds

The service into the modem (co-axial) is 300 mpbs download.  From the Spectrum modem it's via ethernet directly into the Nighthawk Router. Unfortunately, I don't have an ethernet port on my Mac but I ran a few tests to check the speed on the different frequencies on both my Mac and my iPhone with different distances in the house. We also have a Netgear Extender/Booster (EX2700) to help boost the signal to the downstairs area.

2017 Macbook 13"

OS: Mojave 10.14.6

2.3 GHz Intel Core i5

iPhone 12 Pro

sw ver 14.7.1

1. Next to the Nighthawk Router (2nd floor)

Macbook:

5 Ghz - 349 mbs

2.4 Ghz - 79 mbs

2.4 Ghz Ext - 21 mbs

iPhone:

5 Ghz - 345 mbs

2.4 Ghz - 98 mbs

2. Downstairs (kitchen area) directly down the hall (1st floor)

Macbook:

5 Ghz - 210 mbs

2.4 Ghz - 58 mbs

2.4 Ghz Ext - 37 mbs

iPhone:

5 Ghz -  140 mbs

2.4 Ghz - 26 mbs

2.4 Ghz Ext - 28 mbs

After the tests, a few things I was considering... moving the Nighthawk router to a lower position.  It's currently on the top of the 2nd floor landing / staircase.  The position is higher than the 1st floor ceiling but inline with the hallway which leads to the downstairs area; pretty much a straight shot.  Do you think it's possible it may increase the speeds having a more direct line of sight?  The other consideration is buying a dual channel booster/extender to help carry the 5.4 Ghz channel downstairs.  The current extender only supports one 2.4 Ghz channel.  If I remember correctly, the 5.4 Ghz channels have a more limited range.

I'm open to suggestions or next steps.  Thank you.