Couple of questions: The laptop is the initiator of the pings right? You say both machines are on the same VLAN, that's the device that's pinging and the device that's supposed to be answering right? What can the laptop ping? Can it ping anything? If it's a specific device the cause might be an (erroneous) static arp entry on the laptop. On windows you can check the ARP table using the arp -a, see if the IP you're pinging is in there. If it is, check if the MAC-address is correct. Have you made a packet capture on the port the laptop is connected to? This should allow you to see what's going on. You should see the following phases (assuming they're indeed both on the same VLAN): ARP broadcast trying to resolve the IP you're pinging to a MAC address (unless the MAC is already in the ARP cache) ARP unicast reply from the addressee, this lets your laptop know which MAC address it can be reached on ICMP unicast directed towards the just resolved MAC address ICMP unicast reply from the addressee You say you're sure it's the firewall because you have no issues when you connect your laptop to the same switch. What about the same port. Port configuration might not be identical.
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