Not that this scenario fits your circumstances, but just throwing it out there as the issue is similar.

Within a network a terminal server would allow rdp connections, but once connected the internet did not work, sometimes you would get a page but very rare. From a terminal session the internet also failed. Without going into all the troubleshooting, the issue was the NIC hardware settings (NIC properties), and the conflict was between a switch and the router MTU settings.

So, switch and router are pre-existing and work fine. All other servers work fine. Terminal server network connectivity all great, rdp, network shares etc - except the internet. The packets traveling from the NIC into switch which then passes to the router (all other network traffic/testing does not get to the router).

From vague memory it had something to do with the intel NIC "adaptive" technology. disabling these settings resolved the issue. However, setting the switch MTU and router MTU to the same value also proved to be a more permanent solution. (i forgot to mention switch MTU and router MTU had different values.)


[it took 2 days to figure out many years ago]


CTO