Octoprint + Synology + USB Printer mapping HELP

I have a Synology DSM 6.2 running Docker with multiple Octoprint containers since I have three printers.
All my install looks good, the only help I need is mapping the 3D Printer USB connection to the Docker Octoprint instance.
Octoprint displays a message "No serial port found..."
I can see the printer in the Synology CLI (see below)

I am actually trying to migrate from my current Raspberry PI3 because with three instances it makes the print stutters.
Anyway, I would like to get the NAS going. Thanks in advance!!

I would appreciate any help on this, I have done lots of searches and have not found any helpful information.

zeek@Octoprint:/$ lsusb
|__1-2 2c99:000c:0100 ef 2.00 12MBit/s 100mA 3IFs (Prusa Research (prusa3d.com) Original Prusa PRINTER 00000000001A)

Do you see the ports from inside the docker container if you fire up a shell there?