Actually, the question is quite clear. See the MicroLogix Instruction RSLogix help -> MicroLogix Instruction Set -> Selectable Timed Interrupts [STI]. It tells us that STI we can use with MicroLogix 1500 processor only. 5 is the number of STI_IN subroutine that S:31 register contains. BTW "When you are using the MicroLogix Controller the Selectable Timed Interrupt can only be File #5."
I had a similar problem month ago. PLC on-board Ethernet interface has speed 10 Mb/sec. But my laptop's network card has default speed 1Gb/sec. Thus, there was conflict due to different speeds. I changed the speed of laptop network card to 10 Mb/sec and connection was established. By the way, I also tried to use other laptop (older than mine with obsolete NIC) with the same result as you have obtained.