What is the difference between Win7 and WinXP in LAN operation?

Question

Windows

Situation:
in a local network, two PCs are connected to a home network through a DIR-615 router, programs with a TCP server (1st PC) and a client (2nd PC) are running on them. The logic of work:
1) Internal TCP ports 2300 are listened on the server and client
2) On the client, click to find the server - the server connects with a new TCP port (1600 - 1700) to the 2300 client port - the client issues a list of servers.
3) On the client, click connect - the client connects with a new TCP (1600 - 1700) to server port 2300 - the client gets access to the chat, etc.
If the OS is installed on the 1st and 2nd PC:
a) WinXP on both - everything works;
b) On the server - WinXP, on the client - Win7, point 3 is not executed and points 1 and 2 are reset on the client;
c) On the server - Win7, on the client - any, only 1 step is performed.
The last one needs to work.
Turned off the firewall on the PC, added the program to the exceptions - it does not help.
Maybe in Win7 there is a limit on the number of open ports by one program?
P.S. program - cossacs art of war
P.P.S. works without a router in any
P.P.P.S. also works on one PC Win7 if you run both the client and the server at once.

Answer 1

Complex scheme for chat.
There is no difference in the operation of the TCP / IP stack in these operating systems. Firewall blocking is possible, but according to you, you turned off the firewall.
It looks more like this software is not very friendly with Win7 in principle. Try running in compatibility mode e.g.

Answer 2

The internets say to remove all firewall rules (*even if it's disabled, hmm), remove firewallinstallhelper.dll, start the game, try to create a server, alt-tab, allow network activity, re-create the server.
The use of a tambourine is welcome :)

Answer 3

Logs:
Search for WinXP server (.49) on Win7 client (.59): not working:
PID Local Local Remote Remote
05/31/2016 23:57:56 Added 4960 System TCP 0.0.0.0 2300 0.0.0.0
05/31/2016 23:57 : 57 Added 4960 System TCP 192.168.0.59 2300 192.168.0.49 4496
05/31/2016 23:57:57 Added 4 System TCP 192.168.0.59 50315 192.168.0.49 139
Server Selection:
05/31/2016 23:58:03 Added 4960 System TCP 192.168 . 059 50319 178.184.233.162 26056
05/31/2016 23:58:04 Removed 4960 System TCP 192.168.0.59 50319 178.184.233.162 26056
05/31/2016 23:58:07 Removed 4960 System TCP 192.168.0.59 2300 192.168.0.49 4496
05/31/2016 23:58:14 Added 0 Unknown TCP 192.168.0.59 50315 192.168.0.49 139
05/31/2016 23:58:14 Removed 4 System TCP 192.168.0.59 50315 192.168.0.49 139 05/31/2016 23:58:36
Removed 4960 System TCP 0.0.0.0 2300 0.0.0.0
to my external IP (this is only in Win7 so), but to the client .49?
Server search (both WinXP machines): everything works:
PID LocalAdr LocalP RemoteAdr RemotePort
06/01/2016 0:52:29 AM Added 2212 dmcr.exe TCP 192.168.0.59 2300 192.168.0.49 4576
06/01/2016 0:52:29 AM Added 2212 dmcr. exe TCP 0.0.0.0 2300 0.0.0.0
06/01/2016 0:52:29 AM Added 2212 dmcr.exe UDP 0.0.0.0 1252
06/01/2016 0:52:29 AM Added 2212 dmcr.exe UDP 192.168.0.59 639720.
Server selection:
6. 2016 0:53:20 Added 2212 dmcr.exe TCP 192.168.0.59 1256 192.168.0.49 2300
06/01/2016 0:53:20 AM Added 2212 dmcr.exe UDP 0.0.0.0 2350