I can access my scanner on the local machine, but not from a remote host.

Setup:
Printer/scanner server = RPi2, running F27 (cups and sane installed and updated).
Remote system - F27 box, with sane installed and updated. Also, in /etc/sane.d/net.conf, I have a line with my server name. /etc/sane.d/dll.conf has a line with "net".

on the server, "scanimage -L" finds the scanner correctly. From the remote, though, nothing. Looking at the server's saned log, I keep seeing this:

Code:
Apr 27 20:41:35 Pepe systemd[1]: Started Scanner Service (192.168.1.103:34102).
-- Subject: Unit saned@2-192.168.1.100:6566-192.168.1.103:34102.service has finished start-up
-- Defined-By: systemd
-- Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit saned@2-192.168.1.100:6566-192.168.1.103:34102.service has finished starting up.
-- 
-- The start-up result is done.
Apr 27 20:41:35 Pepe audit[1]: SERVICE_START pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=saned@2-192.168.1.100:6566-192.168.1.103:34102 comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
Apr 27 20:41:35 Pepe saned[894]: saned (AF-indep+IPv6+systemd) from sane-backends 1.0.27 starting up
Apr 27 20:41:35 Pepe saned[894]: check_host: access by remote host: ::ffff:192.168.1.103
Apr 27 20:41:35 Pepe saned[894]: init: access granted to ken@::ffff:192.168.1.103
Apr 27 20:41:38 Pepe saned[894]: io/hpmud/musb.c 2099: Invalid usb_open: Permission denied
Apr 27 20:41:38 Pepe saned[894]: io/hpmud/musb.c 2099: Invalid usb_open: Permission denied
Apr 27 20:41:38 Pepe saned[894]: io/hpmud/musb.c 2099: Invalid usb_open: Permission denied
I only get this message when trying remote access. init: access granted to ken@::ffff:192.168.1.103 I think says that saned granted access to the remote box, but then it (saned) can't get access to the usb bus/device (which the local box can). I wrote a udev rule for the scanner:
Code:
SUBSYSTEMS=="usb", ATTRS{product}=="Deskjet F4400 series", GROUP="saned"
but this doesn't seem to do anything different.

I did have this working a while back, same printer/scanner but on an older version of Fedora. But I can't remember if there was something else I needed to do. And, fwiw, the printer part does work over the network.

Any help greatly appreciated.

TIA

ken