Why is the AEBS bottlenecking my ReadyNAS devices leading to bad packets and TCP Retransmits?

Question

Bad Packets Unrecovered TCP Retransmits TCP Retransmits w ReadyNAS NV NV+ and Airport Extreme Base Station 5th Generation
I got an Airport Extreme Base Station (AEBS), 5th generation this past November to bring my entire network up to gigE standards and extend my wireless range a bit. I have really liked the AEBS 5th Gen overall since I got it 3 months ago. It was easy to setup and update and things have been noticeably faster. I can also easily take my netbook, laptop, and iPad out to my shop some 80 feet away from my AEBS and still surf rather well wirelessly too. I couldn't do this even with my previous D-Link wireless-n setup.
In December I picked up an old ReadyNAS NV+ to go along with my old ReadyNAS NV. When I finally started to setup the new network for my business in February, I noticed in the logs that I was getting a large numbers of bad packets, TCP retransmits, and unrecovered TCP retransmits. Previously, I had never had errors of any sort with any older network setups using linksys, dlink and netgear routers during the last 6 years.
Eventually cables, switches, and routers can go bad which results in the errors I have been getting so I went through the "Troubleshoot My Performance Problem/Check for Network Errors" section of the link below to try and figure out what was causing my problem.
(http://www.readynas.com/?p=310#Troubleshoot)
My Initial Setup:
Airport Extreme Base Station (AEBS):
- 1 incoming Cat5e from Motorola Surfboard 6120, 
- 2 Cat5e connections to my wifes work network with her business computer and VOIP phone.
- 1 Cat 5e interconnecting the AEBS to my wired network on the HP Procurve Switch.
The AEBS manages addresses via DHCP on my wired network for all of my devices on the HP Procurve 14008G Switch:
- 1 to NV
- 1 NV+
- 1 MacMini 2010
- 1 MacMini 2005
- 1 networked Epson R-3000 printer
1. Simple things first. Since I have always made all my own Cat 5e cable I figured I'd better get some better(?) cabling strait away. I went ordered new Cat 6 and Cat 6a cables to connect the NV, NV+, and my main Mac to the switch and connect the switch to the AEBS. The errors kept coming.
2. Then I separately connected each NAS unit directly to my computer by setting up the static IP on my computer first. Once I reconnected each ReadyNAS with the computer directly they defaulted to a static IP.  Neither NAS had errors.
(http://sphardy.com/web/readynas/how-to-direct-connect-to-your-readynas/)
3. Errors were coming from either a bad Procurve 1400 switch or a bad AEBS. I hooked everything directly to my Airport Extreme and got lots of errors.
4. I decided to check the switch also. I altered each ReadyNAS's default static IP to one of my choosing individually. Then I hooked both ReadyNAS units to my HP Procurve 1400 switch. I hooked the switch directly to my computer and got no errors from either NAS. I continue to get no errors the next day.
5. When I first ran my tests I had Jumbo Frames turned Off. Currently, Jumbo Frames are On and there are still no errors and seems to be no slowness either.
Conclusion:
The Airport Extreme is the bottleneck causing the errors in my network.
Perhaps there is something I can alter which will rid me of the errors, but this type of error makes the AE seem to be pretty shoddy. A newer state-of-the-art router should not be bottlenecking my rather archaic slow network devices. Apparently, the 4th Gen AEBS's couldn't do Jumbo Frames, but this current model is supposed to, but I see no setting for changing the MTU.
Questions:
What could be causing the bottleneck?
Do I have a bad router?
How could I analyze this problem?
Has anyone else had similar issues and if so how were they resolved?
Current Setup:
All of my computers and NAS devices are hooked to my Procurve Switch each with its own Static IP.
The switch is working flawlessly with no Errors.
The network printer is now wireless and  connected via the AEBS.
I am using wireless-n to connect to internet via the AEBS on my main machine.
I am sharing the internet connection with the other Mac Mini on the switch and any other machine I plug into the switch (not ideal).
Problem is:
I am not a systems administrator and don't really want to tinker with setting up Static IP's for the machines I hook and unhook to the switch.
I want the AEBS to manage addresses via DHCP so everything accessing my router will mindlessly be able to access all things on my network.
Can the AEBS be made to not produce errors or do I just have a lemon.

Answer 1

Hi Bob,
That's the strange thing. When I had both GHz channels working on one SSID, once in a while my iMAC would pick the 5 GHz channel (44 seems the best for me). I always use channel 1 for 2.4 GHz because I get the fastest speeds with it.
When the iMac would pick 5 GHz, the slowdown was very obvious. As I explained in my (long) first post, I immediately felt the difference. Now the $50K question - since the 5 GHz channel at that point was stronger than the 2.4 GHz one, why wasn't the speed faster? Why was it so slow compared to 2.4 GHz? That's what rattling my brain. If the 5 GHz signal's strong enough to get picked by my iMac, then why isn't there a commensurate speed increase? There must be something else going on here besides signal strength. If the 5 GHz spec says that I must have full strength to get 5 GHz speeds, then that makes sense. But I think it doesn't, that's why I believe I have a configuration problem somewhere, or a faulty AEBS.
I might add that my firmware's up-to-date in the AEBS and AX, and Airport Utility too.
I think heading to 4Runner's camp - even with high signal strength (and I would consider 3 of 4 bars high), the 5 GHz speeds aren't showing themselves.
Here's some snap's of my AEBX's setup:
I think my configuration's fine, although I've tried so many different options, I'm a little confused, but I know that changing the Multicast Rate doesn't have any noticeable effect on the speed. I also have "Use Wide Channels" checked, but as I said, the 5 GHz band is awfully slow for using both channels. I have set "N" only, so no "G" clients to slow it down.
Mind boggling!