wireshark vê o pacote antes do firewall na recepção. Isso significa que um firewall ou um produto similar filtra sua recepção. ( referência )
a soma de verificação incorreta normalmente significa que o descarregamento de soma de verificação tcp está ativado no nic.
TCP checksum offloading (lots of checksum errors)
There are causes where you might see lots of checksum errors.
If you capture on a recent Ethernet NIC, you may see many such "checksum errors". This is due to TCP Checksum offloading often being implemented on those NICs and thus, for packets being transmitted by the machine. The checksum will not be calculated until the packet is sent out by the NIC hardware, long long after your capture tool intercepted the packet from the network stack.
As this may be confusing and will prevent Wireshark from reassemble TCP segments it's a good idea to switch checksum verification off in these cases.
To disable checking of the TCP checksum validity, go to the TCP preferences and untick the box for checksum verification