DNS quit resolving for some of my WiFi clients (but not all of them)

Here is my problem:

All WiFi client devices can ping 4.2.2.2. Some WiFi clients can use DNS and others cannot. When a client connects the the WiFi SSID, the client device gets a DNS server assignment of 192.168.x.1 where 192.168.x.1 is the same ip address of the WiFi router on the "local network" side of the WiFi router. So, some clients can use DNS by sending their DNS requests to 192.168.x.1 while others cannot. This configuration was working for months and stopped working today. If I use the NSLOOKUP command in Interactive Mode (on a windows computer), NSLOOKUP works fine if I use an alternate DNS Server (4.2.2.2), however if I use NSLOOKUP with the 192.168.x.1 address, DNS fails.

Here is my configuration:

SonicWALL NSA 2400 - X1 port configured for Cox Communications Broadband Internet Access. SonicWALL port X3 assigned to internal private IP address LAN dedicated to multiple WiFi Routers. WiFi Routers are are NOT configured in Bridge Mode and are connected to a common Class-C, LAN private IP address space with a unique 4th octet.

The "Local Network" side of the WiFi Routers all have their own unique Class-C, Private IP address (or subnet) space for the wireless devices to connect to.

I have attempted to manually assign "known good" DNS servers to the DHCP scope the wireless router configuration, but when the client device connects it just get the IP Address of the WiFi Router not the DNS server I configured.

Any thoughts?

Thanks.
Scott St. HillierAsked:
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Chris HInfrastructure ManagerCommented:
On the wifi routers, set the global DNS server in the wan config to a known public DNS server or your primary subnets internal DNS server/gateway (assuming 192.168.1.1).

Primary router (not wifi)
Wan:
192.168.1.1
255.255.255.0
192.168.0.1 (or whatever)
DNS:
4.2.2.2

LAN:
192.168.5.x

-----

Leech wifi routers:

WAN:
192.168.5.4 (DHCP assigned)
255.255.255.0
192.168.5.1
DNS:
192.168.1.1 or 4.2.2.2
0

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