I have a subnet connected to our network through Cisco 800 series routers using ISDN. I can ping to computers on their end. They can ping to computers on our end. They can receive email from our email server. However, they cannot connect to our network shares nor can they connect to the Internet going through another router, 2500 series, on our end. This is a Windows NT 4.0 LAN. Any suggestions as to where to start looking?