TurboPrint & PrintFab

I have a registered copy of TurboPrint Pro running on Ubuntu 16.04.3.
On the same network (wired Ethernet) is a Canon Pixma PRO-100.
Everything worked fine for a couple days but now the TurboPrint Printer Monitor says the printer is not connected or switched off. No other functions work (can't print, can't check ink levels, ... ).
The printer still works fine from a PC running Windows 7 on the same network.

tcpdump shows network traffic between my Linux machine and the printer when the TurboPrint monitor is running. This exchange happens repeatedly:
06:23:11.931784 IP 192.168.1.3.46364 > 192.168.1.9.8611: UDP, length 16
06:23:11.935814 IP 192.168.1.9.8611 > 192.168.1.3.46364: UDP, length 267

I have tried closing TurboPrint, killing the print monitor process, and restarting. That didn't help.

Hello Tom 239,

what network protocol did you select for the printer? It is shown in TurboPrint Control as "URI" and will probably be "bjnp://..:" or "socket://..".
When you try to install a second instance for this printer via TurboPrint Control (add printer): is the connection for the printer automatically listed and offered? If so, please remove the first printer entry in TurboPrint Control and add the printer again. This reinitializes the print queue and might help solving the problems.

Thanks for the response. The protocol is bjnp. I tried deleting the printer and adding it again (TurboPrint does find the printer when I ask to add) and I am still experiencing the same problem.