Persistent "Printer in use" Error

I've been having a persistent problem with a "Printer in use" error on one of our network printers.

Here's what I tried and did not work:

1. Delete and reinstalled the printer with LPD Protocol 
2. Tried adding printer with IPP Protocol (printer not recognised)
3. Delete and reinstall the printer driver.
4. Resetting printing system, was also unsuccessful (I've tried this 3 times.) 

The machines that are giving me trouble are:

1. MacPro 10.12.6
2. MacBookPro 10.12.6

The printer works fine with:

1. iMac 10.12.6 - The Computer is able to send print jobs to the network without any problems.

Background:

1. All of the computers are networked together and they talk to each other without any problems.
2. The printer worked fine with the prior system on The MacPro. The machine had a system crash due to system privileges. Everything was reinstalled from scratch to avoid contaminating the system with prior preferences.
3. The printer is a Dymo LabelWriter 4XL, connected to a router via USB.
4. I know that the address for USB connected printer is the router IP
5. The router has USB printing enabled (the other machine can print without any problem)
6. The printer works fine if connected directly to MacPro
7. The MacPro was able to send job to the printer prior to the crash
8. While troubleshooting I tried the setting up network printing on the MacBookPro but I get the same error when sending print jobs "Printer in use"
9. I’ve reinstalled the exact print driver version that worked originally with the MacPro
10. At the moment we are staying with Sierra as we are in a production environment and upgrade is too time intensive.
11. WORK AROUND - The iMac is now sharing the Dymo printer, if I add the printer on the MacPro I’m able to print. That means that the data sends fine from my computer through the network. This solution is not ideal because it requires the iMac to always be online.

This is what I deduce:

The issue must lie with how I’ve add the printer to the MacPro and the MacBookPro. I must have done it right the first time around, with the iMac, but not now. This is how I go about it step by step:

1. I reset the printing systems
2. Add a printer by pressing “+“ 
3. Select IP

• • Choose Line Printer Daemon - LPD as protocol
  • Enter the router address in the address field
  • Select the corresponding driver to the printer in the use field.

4. Printer is added and I get a green light next to it.

5. I send a job to print and this is what I get in the print queue. Nothing prints

6. And this is what the system preference looks like when the “printer in use” error shows up

7. if I delete the print job the Printer goes back to idle.

I've searched the web but there are no solution to this issue that I can see. Any help would be greatly appreciated.