S7-1200 Modbus TCP no connection

I have a new 1211C to play with so I decided to test its Modbus TCP instruction.
I have followed the guide below but it seems that I can't establish connection.
https://www.dmcinfo.com/latest-thinking/blog/id/8869/using-an-s7-1200-plc-as-a-modbus-tcp-slave
I don't have a hardware client so use software modbus TCP client emulators like http://www.simplymodbus.ca/TCPclient.htm
http://www.modbustools.com/modbus_poll.html

I can download my program to the PLC but I have no connection through Modbus TCP.
What could be the problem?

I've never used this type of controller before, but I have used Modbus TCP/IP. I do know through my experience that choosing the right port could have an impact whether or not you are going to communicate. If this controller has that option.

I have attached my setup.
The IP and the port are matched properly but still I can't connect.

Found the problem.
Some program was using the port 502 and I couldn't connect.

Congrats!!! It's always a great feeling to find the problem isn't it!!