15 users behind a Server 2012 DNS server. Lots of "webpage cannot be displayed". Hit the refresh button and it pops right up. Turn on DNS logging in the server, and lots of DNS packets time out. Put my laptop into the firewall, set the DNS to 8.8.8.8 or 4.2.2.2 and I get the same symptoms. Plug my laptop straight into Comcast's router (which is set as a bridge) and everything is happy.
It's obvious this is the dead end. I have the latest firmware, 1.09B38_WW. When I search the logs for port 53, I see a lot of this:
[DSR-500][Kernel][KERNEL] same_src : Invalid address same_src : Invalid address [] LOG_PACKET[ALLOW] IN=SELF OUT=LAN SRC=192.168.50.1 DST=192.168.50.2 PROTO=ICMP TYPE=3 CODE=3 SRC=192.168.50.2 DST=75.75.76.76 PROTO=UDP SPT=63121 DPT=53
192.168.50.1 is the firewall, 192.168.50.2 is my server, 75,75.76.76 is Comcast's DNS.