My BI works well n the network all the time and also off network for a short while and then I lose connection. Any ideas as I rule out a permission or port access issue. Also my PC and router both seem to keep a consistent IP.
Did you set up remote viewing via UPnP? If so, some routers will remove UPnP rules without adding them back. If you are port forwarding, use port forwarding rules instead of UPnP and make sure your BI machine has a static IP.
+1 on everything that @TonyR said, good info there.
It's a matter of going into network settings on the PC, looking at its status to see what was assigned by DHCP, write that down, go into the Ethernet adapter's IPv4 properties, type in that written-down IP, use subnet mask of 255.255.255.0, gateway IP will be your router's LAN IP, primary/preferred DNS will be same as gateway, click on "OK".
Log into your router and reserve that IP that you set above for the BI server.
If too much, use your google fu to look up how-to change the IP on your particular Windows flavor.