Communication between UR + mir +PC

Hello,

I did a communication with UR 10 e+mir200 MODBUS
After I did a communication with UR ( the client) +PC (the server) with TCP/ip SOCKET

When I test them separately, the communication is function

But when I make a switch ( a modem) and I made the three devices to communicate I can’t open socket between robot UR and PC (the PC lost communication with PC) but the communication between UR and Mir is still function.

The instructions are: The robot mir move to frist position after it is activate UR program and in the UR program the robot should communicate with PC ( socket communicate) ( but when the mir is connected, the robot can’t communicate with the PC)

Are there any help to resolve this problem.

Thank you !