RX50 2.4g download speed very slow

i really appreciate everyone digging into this and am impressed by all of your expertise.  Below are more answers:

What Firmware version is currently loaded?

Most recent for the RX50 and no new updates available as I checked <What is the exact version please.

The RAX50 I own has no rev number so the label says RAX50 only.  The Firmware version is: V 1.0.12.120_2.0.83 and according to Netgear is the latest version for this unit

What is the Mfr and model# of the Internet Service Providers modem/ONT the NG router is connected too?

I use a Netgear COX (my ISP) certified CM1100 which is connected to my Netgear RX50

Be sure your using a good quality LAN cable between the modem and router. CAT6 is recommended. 

LAN cable if fine. <What CAT# is this "fine" cable?

I am using CAT5 which is what I have been using since I installed the units.  Anything hardwired is also CAT5 and the devices are all operating fine.  My biggest issue is if I use 2.4Ghz on my Macbook (so of course I am using 5Ghz for my Macbook which is the one I use most of the time) or iMac using Wifi, download is very slow which is odd as some of the other devices are using Wifi 2.4Ghz and stream fine??

CAT5 is only officially supporting of 100Mbps. To get best speeds and operation performance CAT6 should be used to ensure the connection rate is getting the full 1000Mpbs speed. 

Thanks.  I will get a CAT6 cable between the Modem and Router.  With that said probably will not at this time go through the expense of rewiring the house wherever I am using Ethernet to CAT6

What connection rates are you seeing with devices connected on 2.4Ghz. 

Getting very good rates and even have some streaming using 2.4Ghz <What exact connection rates are you seeing with your devices on 2.4Ghz?

What devices do you have that your connecting to 2.4Ghz?

- iMac

- Roku 186 (Rarely used)

- Blink Camera Module

- Blink Mini Camera (Rarely used)

- Amazon RX-A3080 (Rarely used)

- Apple TV (Rarely used)

- Printer

- iPhone SE

So my iPhone SE using 2.4Ghz is getting 84Ghz (plus or minus depending on traffic)

Do you mean 84Mbps? 

Yes

Is Smart Connect enabled or disabled?

Smart connect is not enabled nor would I enable it as some of my devices cannot toggle to 5 from 2.4 and has been disabled since I have configured my set up for 3 years now

Do your devices connect or get good speeds with SC enabled?

Yes 

Do you have 40Mhz channel width set?

20/40 Coexistence is enabled < Set 40Mhz only on 2.4Ghz

Only allows to enable disable 20/40  Nothing to set it only for 40Mhz that I can find in the BASIC>WIRELESS TAB>Under 2.4Ghz

By UN-Checking the check box seen here, sets 40Mhz only mode of operation. 

Will do this.  Will it buy me anything?

Most 2.4Ghz devices will cap out at anywhere from 50 to 100Mpbs depending on there design and support. 2.4Ghz mostly will never see speeds near 800Mpbs. " 2.4GHz AX: 2x2 (Tx/Rx) 1024/256-QAM
20/40MHz, up to 600Mbps" <This is a connection rate only between the router and wifi devices that support this connection rate. This differs from bandwidth speeds.

Fully agree about the Cap out rates, but previously I have gotten at least 300 Mbps.  I also know it is not the Modem as of course (stating the obvious) when I cam using ethernet the speeds are much higher for Download.  If you think of anything else please let me know.

Is 300Mpbs the bandwidth speed or the connection rate?

I am no longer getting anywhere near that and I recall was the connection rate.

AT THIS POINT AND AFTER READING MORE INFORMATION FROM YOU GUYS AND THE LINKS YOU GUYS SENT, I AM CONVINCED THAT SOMEHOW WHAT I HAD SEEN PREVIOUSLY MUST HAVE BEEN AN ANOMALY.   I APPRECIATE THE EXCELLENT SUPPORT FROM EVERYONE THAT HELPED WITH QUESTIONS AND ANSWERS TO MY ISSUE.  I OF COURSE WILL USE THE 5GHZ FOR IMPORTANT DOWNLOADING AND LET THE OTHER DEVICES USE THE 2.4GHZ.  JOEL

Please don't use CAPs, no need to yell, we can hear you fine.

I used caps to ensure everyone knew how much I appreciated the inputs and time spent on this issue I am old school and did not realize caps meant yelling when send messages.  LOL.  Thanks again to all.