Error 1231 is a network problem that occurs due to connectivity problem or network trouble shooting. When this problem occurs, the information displayed on the screen is; - ‘location network cannot be reached’. Due to this problem, physical computers are unable to connect to the internet. Error code 1231 is associated with Windows Vista. Once it occurs, one cannot ping his or her own IP or default gateway because once one tries to ping this gateway the resultant error reads, ‘ping transmit failed error code 1231 message. When this problem occurs and that one is using V6, try deselecting TCP IP V6 setting under the LAN adapter. This seems to favor V6 over V4 since it is thought that this could cause the problem.
Once the error code message is displayed, first confirm whether the cable/port/switch port configuration is ok. If one is able to ping the local host, then one could also try pinging the assigned IP address, if that responds, then one is free to try pinging the gateway, if again there is no response it is recommended to check the speed and duplex settings on the card as well as the subnet mask setting. If that still does not solve the problem, one can set up a simple DHCP server and see if they can connect through this way. If all these fail, try another NIC.