A public IP address, which is what the world sees, should be the same for all the computers, when going through a router, or router/modem (combo). It is the router, or router/modem (combo) that acts as a "traffic cop", and directs incoming to the appropriate computer on your network. However "private" IP address, what your router, or router/modem (combo) gives out to the computer, etc connected to it, that is a different story. Each device off your router must have a different IP address.
1. Check the configuration of ALL the computers, and see if they have the same ip address. This is presuming that they may have static IP addresses assigned. This is done in the networking area. Make sure that they all are set to DHCP.
2. Power down ALL PCs.
3. Do a hard reset on the router, or router/modem (combo). So this my pressing a small recessed button somewhere on the router/modem. Usually you have to use a paperclip or something similiar, and hold the button down until the light flicker, maybe 10-15 seconds.
4. Power on one of the computers. Let it cycle up, and check your connection.
5. Power on another one of the computers. Let it cycle up, and check your connection.
6. Power on the last computer. Let it cycle up, and check your connection.
If none of this works, then contact your ISP. It is possible that the firmware update hosed things. To my knowledge, once a firmware upgrade is done, there is no way, short of finding the older firmware file, to go back.
Best of luck.
Edited by scotty_ncc1701, 25 June 2014 - 04:39 PM.