Samsung SCX 4729-FD ADF only receives one page: Error during device I/O

It's all in the title.

• I did manage to get another error once: Something about no more paper in ADF.
• I had to reboot the printer a lot, because it hung and disappeared.
• I'm running it on a banana pi m2. Everything else works there.
• Tried with and without USB hub in between.
• Also tried via network instead of USB, same issue.
• Flatbed works fine with several pages.
• Flatbed also scans ADF if paper inserted in ADF (the setting Flatbed/ADF/Auto seems to have no effect)
• 600 dpi produces a bad first page.

My issue seems surprisingly similar to these:

• error during device I/O (canon): #30 (closed)
• USB scanner not detected (xerox_mfp): #15

My sane version: Debian (Armbian): 1.0.14-12

debug log:

Scanning page 2
[dll] sane_start(handle=0x1d12280)
[xerox_mfp] sane_xerox_mfp_start: 0x1c94410
[xerox_mfp] :: dev_command(RESERVE_UNIT[0x16], 32)
[xerox_mfp] usb_dev_request: sanei_usb_read_bulk: Error during device I/O
[xerox_mfp] dev_command: dev_request: Error during device I/O
scanimage: sane_start: Error during device I/O
[dll] sane_cancel(handle=0x1d12280)
[xerox_mfp] sane_xerox_mfp_cancel: 0x1c94410
Closing device
[dll] sane_close(handle=0x1d12280)
[xerox_mfp] sane_xerox_mfp_close: 0x1c94410 (libusb:001:022)
[xerox_mfp] usb_dev_close: closing dev 0x1c94410
Calling sane_exit 
[dll] sane_exit: exiting

$ sudo SANE_DEBUG_DLL=128 SANE_DEBUG_SANEI_USB=128 scanimage -L 2> log.txt
device `xerox_mfp:libusb:001:023' is a Samsung Samsung SCX-472x Series multi-function peripheral

log.txt