Do the old router and the new router used the same network address range?
An ip address is made up from two parts - a network address and a host address - if your ip address is 192.168.0.102, the 192.168.0 is network, and the 102 is the host, if your ip address is 192.168.1.10, the 192.168.1 is network, and the 10 is the host (I'm trying to keep this simple, so we're ignoring the network mask).
If the network address is different, as I suspect may be the case, your problem is most likely caused by a software firewall or internet security suite blocking access to the new network range, because it sees it as "untrusted".
Either configure the new router to use the same range as the old router, or reconfigure the security software to trust the new range.