ReadyNAS Ultra 2 can't print anymore after 4.2.24 upgrade

I have a Readynas Ultra 2 with a Brother HL1450 printer connected to it. Since the upgrade to 4.2.24 it is impossible to print through the NAS.
Disconnecting and reconnecting the printer (even on other USB ports), rebooting the NAS, reinstalling the printer to the computers... Tried all that but it's still not working.
The printer is detected by the NAS (it is listed on the printer cue page). The printer is also discovered correctly in the dmesg log:
usb 3-1: new full speed USB device using uhci_hcd and address 2
usblp0: USB Bidirectional printer dev 2 if 0 alt 0 proto 2 vid 0x04F9 pid 0x000E
usb 3-1: USB disconnect, address 2
usblp0: removed
usb 3-1: new full speed USB device using uhci_hcd and address 3
usblp0: USB Bidirectional printer dev 3 if 0 alt 0 proto 2 vid 0x04F9 pid 0x000E

When I print something to the NAS, the computer keeps "spooling", but nothing appears on the print cue on the NAS webpage.

Kind regards,

Stijn