Remote host did not accept data file (32) when printing.

Currently having issues with printing to an Epson R3000 printer - print will start but partially through the print (randomly 20-95%) the CUPSD transfer rate on the iMac will drop to 0, then R3000 printer stalls and stop printing with the message - Remote host did not accept data file (32)

Printer is connected to iMac (OSX 10.11) via Asus RTAC68 router.

Printer works fine when printing direct from Iphone/Ipad and also directly to the same iMac when using computer to computer network.

All printer drivers/firmware updated along with router firmware upgraded.

If anyone has any suggestion on what may be causing this issue it would be greatly appreciated.