ok the reason that it only happens only with the Dlink is that it is the only router I have that supports Ipv6.

The Fix is to disable ipv6 in firefox. Aparently many more people have been having this problem.

type about:config in firefox

type ipv6 in the find box

change the disable ipv6 line to true

restart firefox


I assume the same fix will apply to Iceweasel