R8000 significantly slower 2.4 than 5.0

[s21slm]

My 2.4 speed vs my 5.0 speed is showing large differences. The attached picture tests were all done on the same device (samsung note 9). First 2 were on 5.0 second 2 on 2.4.
Are these speed differences normal?

[s21slm]

Just to add to this I was running the latest firmware, I have factory reset and no changes,
I have now rolled back to .28 and still no changes

[plemans]

2.4g is significantly slower than 5ghz and its more sensitive to interference. Especially in environments where there's a lot of signals (condos, apartments, homes close together)
I live in a detached home and prior to AX rarely sustained speeds >30mbps over 2.4ghz. 

[s21slm]

Thanks for the update,
My modem is running 500M. If I use my ISP router the speeds of 2.4 are considerably higher. Prior to me rolling back the firmware it was even worse which leads me to believe the issue must be R8000 related

[plemans]

what modem is your isp's device? 

What speeds do you get with it? 

How are you testing the speeds on it?