We have two Buffalo WZR-HP-G300NH2 routers, with the default firmware, DD-WRT v24SP2-MULTI (10/31/11) std - build 17798. Each has a separate cable internet connection with a public static IP address. They are both in the 18.104.22.168/24 space.
Both of them can contact pretty much the whole internet, and they can both be accessed out on the internet with no problem, but for some reason they can't talk to each other! When I try to ping one from the other I always get "Destination Host Unreachable". There are no strange routing or firewall rules in place. And they are both set to respond to pings, I can ping them from outside.
Our main IT guy is going to call our ISP on Monday, but I'm impatient, so does anyone have any ideas?