What can be preventing comunication between two computers?

by Stijn Vogels

Question by rag3000: What can be preventing comunication between two computers?

I have a small network. There are two computers wired to a switch. The remaining are laptops conected through wireless. All computers have comunication with each other. The big exception are those computers wired to the switch that doesn't have comunication between them, however both have comunication with all wireless laptops. What could be preventing comunication between this two?

Both have static IP, are in the same Ip range, same subnet mask, same gateway (although not needed), firewall turned off... And a simple ping does not get response.
It can't be IP conflict. If that were true one of the wired computer computers (or both) shouldn't have communication with nothing.

DHCP is not a suitable option. Currently one of the wired computers is a domain controller, the other one will be a server too. However, I will try DHCP in the later for testing purposes.

The switch is a combined device... I will check device rules. However, I believe that this is not the right way. Before friday, wired computers had communication between them and no changes to the device has been done.

For software firewalls, Windows Firewall is disabled (even windows the service that provides this feature). I recently uninstalled McAfee and no success. I don't know what else could be causing the problem.

If nothing solves the problem, I will try system restore. If this doesn't solves the problem, I will try a live OS. If the live OS works... I will end up formatting that computer.




Best answer:

Answer by Wolf
There are a few possibilities, so you might want to check the following:

- Any software firewalls you may have on the wired PCs (Windows firewall in particular can do strange things for this)
- Your "switch" might be a combined device, being a router/wireless AP, in which case it might have its own internal firewall that shields PCs from each other that are connected to the wired ports (most likely case), check for "LAN/LAN" traffic rules.

Give your answer to this question below!