Welcome to EpoS Wizard!
I’m having a bit of a mare with my till system (running ICR Touch) at one of the restaurants I manage.
Basically on of the KP printers (which is on the network) it prints out all the kitchen orders - works fine. However we recently set up a click and collect service (using our own bespoke system) which needs to print at the same printer too (so the kitchen knows what needs to be made).
I tried to set up the same printer using the same IP on a different dedicated windows PC just for the click and collect. I tested a print and it all worked fine however the printing via the till stopped after doing this - displayed device error?
I don’t understand why this happens as the printing from both are two separate systems and all its doing is sending to the IP network printer.
Not sure if this makes any sense but could someone advise where I am going wrong or a possible solution to this? Or is it even possible to have something else print to one of the printers the till is using?
by your own admission, the printer was working fine until you added your own bespoke software - i guess this lets ICRTouch off the hook here.
Is the coding on your bespoke software continually polling the printer or something similar? Hiding the port port from ICR? [i'm no programming expert though] 
I reckon that your own software is locking the IP printer so that it is unable to respond to the ICR software when that tries sending a kitchen ticket.
You're going to be able to get zero help on here with your software, so I'd suggest you just buy a second printer for your kitchen instead.
This is because you have a windows printer on your network blocking port 9100.
Get another printer as Simon said. 
