It was not difficult to communicate a Koyo PLC with VTScada by means of Modbus TCP, being both, PLC and VTScada in the same LAN.
However, I have not been able to communicate them when the PLC is connected to a router outside the LAN of VTScada.
I typed a public IP address and the PLC port number when configured the TCP/IP port in the VTScada.
The resulting value of TCP/IP Port is -10,061.
Question is: Is this possible to connect a remote PLC to VTScada that way?

I've seen that a few times. All of them I found I did not have a route to the I.P. and/or port of the Click PLC in the field.

Is port 502 mapped in the field router to the static local I.P. of the PLC?

If the path is resolved correctly, there is no reason I can think of as to why this shouldn't just work. I connect VTScada to PLCs via a VPN on a regular basis.