Not always receiving default gateway over wireless

I have an odd one here and can't seem to find an answer through google.

I have a windows 2008 domain with a DHCP server on a windows 2012 server. We have 2 Cisco WAP371 access points. All ethernet connected computers receive all TCP\IP info no problem. WiFi devices connect to the wireless (2.4 GHz or 5GHz) and receive everything except Default Gateway as below.
Wireless LAN adapter Wireless Network Connection:

Connection-specific DNS Suffix . : d178120.com
Description . . . . . . . . . . . : DW1501 Wireless-N WLAN Half-Mini Card
Physical Address. . . . . . . . . : 68-A3-C4-10-23-0C
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IPv4 Address. . . . . . . . . . . : 10.51.51.106(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Lease Obtained. . . . . . . . . . : Friday, July 22, 2016 1:30:26 PM
Lease Expires . . . . . . . . . . : Saturday, July 30, 2016 1:30:26 PM
Default Gateway . . . . . . . . . :
DHCP Server . . . . . . . . . . . : 10.51.51.76
DNS Servers . . . . . . . . . . . : 10.51.51.20
10.51.49.20
NetBIOS over Tcpip. . . . . . . . : Enabled

If I do an ipconfig /release then ipconfig /renew it then gets everything including the default gateway. This just started happening the last 3 weeks or so with no new equipment or any changes that I am aware of. I have power cycled both Cisco access points as well as the switches they are plugged into and the DHCP server. I just don't understand why it would only be wireless devices and why a simple release and renew would work. It's different computers including Dell Latitudes, HP Probooks, and Microsoft Surface Pro's so not tied to a particular NIC manufacturer or anything. Any advice would be appreciated.
 
I believe it is a 'timing race condition' created by attempting to get both wired & wifi connections on the same box. Can you confirm only one connection is attempted per machine or is every failure on a machine attempting both connections?
 
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