[lwip-users] tcp communication problem with server and client on different subnets

[lukasz139]

Hi,

I would like to ask for advice and expertise with my problem. I use raw API
without OS. 

I have an application on tm4c1294 running a tcp server. For both static IP
configuration and DHCP it works completely fine on the same subnet. When the
client tries to establish socket connection from different subnet it fails.
There is no frame with ACK flag in the response to SYN flag. I see that it
fails to do the handshake (I use wire shark). I have doubled check the
subnet and gateway settings, also if I use DHCP from what I have read in
documentation of LWIP library gateway and subnet should be assigned with
dynamic IP.

The ICMP frames of ping command reach correctly on both LAN and in the case
of different subnets. It suggests that gateway settings should be correct...
Is there any smart way to investigate that? Checking if any firewall on  my
way blocks?

I know it doesn't have to be problem related to lwIP itself but I will
appreciate clues from experienced users.

Thank you.



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