I set up a Cisco 871 router that connects a network A and network B.
Network A has one Linux laptop with one NIC.
Network B has one Windows PC with multiple NICs.
I configured 2 VLANs along with static routes.
I ping from A to B and use Wireshark (filter string = icmp) to monitor traffic on both A and B.
On A network, I can only see requests (ICMP packets) coming to B but no replies from B.
On the other hand, I can see Replies from B to A but no requests.
There's no connectivity between A and B.
Yet, if I diable other NICs on the Window PC, I see both request and replies on both sides and there's connectivity.
Can someone explain why ? How do I enable connectivity without bringing other NICs down ?