CCR1036-12G-4S
v6.24

PPPoE server set up on the CCR, client routers can authenticate successfully and resolve DNS and ping public IP's. Client routers get assigned appropriate DNS servers, but that information fails to pass to client devices. Client devices behind client routers can ping public IP's but cannot resolve DNS. Manually setting DNS servers on client routers has no effect, but manually setting DNS servers on client devices does work. This seems to be affecting certain Dlink, Netgear, and Linksys routers, regardless of firmware updates. It's like implementing the CCR1036 has prevented some client routers from functioning as DNS servers for their local network.

DNS settings on the CCR:
Allow remote requests - checked
Max UDP Packet Size: 4096

Could the max UDP packet size be too big? I've read here ( http://stackoverflow.com/questions/1098 ... e-internet ) that setting it too high can cause issues.

I have firewall rules on the forward chain accepting tcp and udp port 53. Both counters are active and climbing. Like I said, this only affects about 5% of our clients, if that. The weird thing is that DNS traffic is failing to be passed by the client ROUTER to client devices, but this problem was brought on by replacing our former core router with the CCR.

I set the max UDP packet size to 512. Still no effect. DNS traffic seems to pass for a while, then nothing again. Any ideas are greatly appreciated.