Hi,

This could all just be a configuration issue on my part, but I'm a bit stumped at the moment.

I've just got a 2860n plus to replace a 2820n.
I have 2 WAN connections - WAN1 ADSL via EE and WAN2 cable broadband from Virgin.

So...in general everything works fine, but I've found I can no longer have the DNS server on client machines set to the router's IP address and get any DNS resolution if they're using WAN2.
Everything works OK if I explicitly set, say, Google's DNS servers on client machines, but I don't really want to do that across all my machines.
With the 2820n (latest firmware) this worked fine, but it could be that I set up something specific with the 2820n that I missed when installing the 2860n plus.

At the moment, I have the following setup:

WAN -> Internet Access -> WAN2 -> Static or Dynamic IP
DNS Server IP Address
Primary IP Address: 8.8.8.8
Secondary IP Address: 8.8.4.4

LAN -> General Setup -> LAN1 -> Details Page -> LAN1 Ethernet TCP/IP and DHCP Setup
DNS Server IP Address
Primary IP Address:
Secondary IP Address:

The latter is based on the manual saying this: "If both the Primary IP and Secondary IP Address fields are left empty, the router will assign its own IP address to local users as a DNS proxy server and maintain a DNS cache. If the IP address of a domain name is already in the DNS cache, the router will resolve the domain name immediately. Otherwise, the router forwards the DNS query packet to the external DNS server by establishing a WAN (e.g. DSL/Cable) connection."

With this setup, the Online Status -> Physical Connection screen still shows this though:

LAN Status Primary DNS: 87.237.17.168 Secondary DNS: 87.237.17.200

...which look to be the DNS servers of the WAN1 EE connection.

If I do actually enter Primary/Secondary IP addresses for, say, Google DNS, on the LAN DHCP setup, it seems to to make no difference to what's listed there.
The LAN DNS server settings listed are always taken from the WAN1 ADSL connection, and I don't see a way to influence that.

So, I guess my questions are:

* Is it possible to have client's just use the 2860's IP address for a DNS server and rely on the 2860's proxy/caching to do the "right thing" based on its cache and the WAN connection the specific client is using?
* If so, how do you ensure this happens ?

Thanks.

As a follow up, I've just found the following option:

LAN -> General Settings
Force router to use "DNS server IP address" settings specified in LAN1

...although in a different place than in the manual, hence I missed it.

That seems to solve the main problem i.e. if I then set Google's DNS servers for LAN1, and have the above option checked, I can use the router's IP address for a DNS server and DNS for all WAN connections is resolved through Google's DNS. That's probably how I had things on my 2820n.

I'm sure this is just ignorance on how all this works, but I have a couple of questions:

* Does the above setup, that I'm now using, benefit from any router DNS caching?
* Is there a way use the router's IP address as the DNS server and have the appropriate ISP's DNS servers used based on the specific WAN connection that the client is using at the time?