New to Java

Hi All,
I have developed a chat application using socket programming . When I tried to test the application in LAN the server was unable to establish connections with few clients later I have identified that my application was able to establish connections with in certain range of IPs

For Example:
These are the 3 different sets of IP ranges I have in my LAN
1.xxx.xxx.232.num (num ranging from 130-200)
2.xxx.xxx.232.num (num ranging from 200-250)
3.xxx.xxx.229.num (num ranging from 10-50)

So if the server is present in first range then it will establish connections only with the IPs that are present in that range the other IPs will not be connected.
Note: ping command also fails between this different range set of IPs
Is it the case like socket programming can be done only when all the IPs are present in the same Subnet and all should be served by only one router? If not please tell me how to establish connection between different Subnets and different router configurations using Socket programming.
If it is not possible using socket programming is there any other means to communicate between different subnets and routers

Thanks in advance