Two ISP's with two blocks of Static ip's One block split by switch and then into a series of routers, then into internal network to web servers, PC's and proprietary comm. devices Second block using one ip into own router, then into other devices inside. *These networks then shared by unmanaged internal switches (not my doing) * Symptoms: 1) internal computer will periodically pick up different external IP addresses (using IP Chicken) 2) Internal comm. device often addressable on 123.xxx.xx.82 drops and can only be seen on 456.xxx.xxx.67 ; it must be seen by 123.xxx.xx.82. This crossed system was seen by client as a means of redundancy. I assume I must disable any internal communication between these networks ?