saned not working in Trusty, Utopic, or Vivid

[penalvch]

Following verbatim https://help.ubuntu.com/community/SaneDaemonTutorial previously worked in Trusty with my HP OfficeJet 5610v All-in-one plugged into a USB 2.0 port, where the Trusty server had a wireless interface setup as a WAP for clients to connect directly to. However, it now no longer works in Trusty when instead ethernet through a switch or via WiFi router, and doesn't work in Utopic or Vivid. For example, in Windows 8.1 with SaneTwain 1.3.6, it used to work. Now it pops up a window:
Error
No devices found on backend.

However, in the Device drop down it notes:
hpaio:/usb/Officejet_5600_series?serial=XXXXXXXXXXXXXX

Ubuntu 15.04 client with either xsane or simple-scan doesn't find anything. Running the following from a terminal results in either a crash or no SANE devices found as per https://bugs.launchpad.net/ubuntu/+source/sane-backends/+bug/1442960 :
scanimage 192.168.1.15
scanimage: no SANE devices found

scanimage 192.168.1.15
*** Error in `scanimage': double free or corruption (!prev): 0x00007f5a939fff10 ***

The scanner works fine locally on the server via simple-scan and xsane.

Intermediary device networking being the root cause has been ruled out as I connected the server and client via ethernet through a switch, disabled wireless and still reproducible. Confirmed clients and host may ping each other.

Tried disabling ipv6 on just and both server and clients, no change.

= Trusty Server (upstart) =

+ 12.04 Client attempting to connect:
SANE_DEBUG_NET=128 SANE_DEBUG_DLL=128 scanimage -L net:192.168.1.6
https://bugs.launchpad.net/ubuntu/+source/sane-backends/+bug/1442956/+attachment/4388269/+files/SANE_DEBUG_NET%3D128%20SANE_DEBUG_DLL%3D128%20scanimage%20-L%20hpaio%3Anet%3A192.168.1.6

= Vivid Server (systemd) =

scanimage --device net:localhost
scanimage: open of device net:localhost failed: Error during device I/O

sudo systemctl restart saned.service && sudo systemctl status saned.service -l
● saned.service - Scanner Service
   Loaded: loaded (/lib/systemd/system/saned.service; static; vendor preset: enabled)
   Active: inactive (dead)

Apr 22 19:40:24 pc systemd[1]: Unit saned.service entered failed state.
Apr 22 19:40:24 pc systemd[1]: saned.service failed.
Apr 22 19:40:24 pc systemd[1]: Starting Scanner Service...
Apr 22 19:41:31 pc systemd[1]: Started Scanner Service.
Apr 22 19:41:31 pc systemd[1]: Starting Scanner Service...
Apr 22 19:41:31 pc saned[2545]: saned (AF-indep+IPv6) from sane-backends 1.0.24 starting up
Apr 22 19:41:47 pc systemd[1]: Started Scanner Service.
Apr 22 19:41:47 pc systemd[1]: Starting Scanner Service...
Apr 22 19:41:47 pc saned[2574]: saned (AF-indep+IPv6) from sane-backends 1.0.24 starting up
Apr 22 19:41:47 pc saned[2574]: check_host: access by remote host: localhost

    journalctl -xe
    Apr 22 20:04:41 pc sudo[2669]: pam_unix(sudo:session): session opened for user root by USERNAME(uid=0)
    Apr 22 20:04:41 pc polkitd(authority=local)[979]: Registered Authentication Agent for unix-process:2670:337819 (
    Apr 22 20:04:41 pc systemd[1]: Got more than one socket.
    Apr 22 20:04:41 pc systemd[1]: saned.service failed to run 'start' task: Invalid argument
    Apr 22 20:04:41 pc systemd[1]: Failed to start Scanner Service.
    -- Subject: Unit saned.service has failed
    -- Defined-By: systemd
    -- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
    --
    -- Unit saned.service has failed.
    --
    -- The result is failed.
    Apr 22 20:04:41 pc systemd[1]: saned.service failed.
    Apr 22 20:04:41 pc systemd[1]: Starting Scanner Service...
    -- Subject: Unit saned.service has begun start-up
    -- Defined-By: systemd
    -- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
    --
    -- Unit saned.service has begun starting up.
    Apr 22 20:04:41 pc sudo[2669]: pam_unix(sudo:session): session closed for user root

/lib/systemd/system/saned.service :
https://bugs.launchpad.net/ubuntu/+source/sane-backends/+bug/1442956/+attachment/4383859/+files/saned.service

/lib/systemd/system/saned.socket :
https://bugs.launchpad.net/ubuntu/+source/sane-backends/+bug/1442956/+attachment/4383860/+files/saned.socket

/etc/default/saned :
https://bugs.launchpad.net/ubuntu/+source/sane-backends/+bug/1442956/+attachment/4385534/+files/saned

/etc/sane.d/saned.conf :
https://bugs.launchpad.net/ubuntu/+source/sane-backends/+bug/1442956/+attachment/4388266/+files/saned.conf

Following verbatim did not work:
https://lists.fedoraproject.org/pipermail/users/2014-December/456319.html

Related report focusing on my scanner's driver:
https://bugs.launchpad.net/ubuntu/+source/hplip/+bug/1448467

Posting as a reference, may or may not be relevant:
https://bugzilla.redhat.com/show_bug.cgi?id=1091566

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: sane-utils 1.0.24-1.1ubuntu1
ProcVersionSignature: Ubuntu 3.16.0-34.45-generic 3.16.7-ckt8
Uname: Linux 3.16.0-34-generic x86_64
ApportVersion: 2.14.7-0ubuntu8.2
Architecture: amd64
CurrentDesktop: Unity
Date: Sat Apr 11 14:56:27 2015
InstallationDate: Installed on 2015-04-09 (2 days ago)
InstallationMedia: Ubuntu 14.10 "Utopic Unicorn" - Release amd64 (20141022.1)
SourcePackage: sane-backends
UpgradeStatus: No upgrade log present (probably fresh install)
mtime.conffile..etc.default.saned: 2015-04-11T13:29:50.323836
mtime.conffile..etc.sane.d.saned.conf: 2015-04-11T14:30:15.645215

[penalvch (penalvch)]

Works for me in Xenial via systemd. Will update documentation at https://help.ubuntu.com/community/SaneDaemonTutorial with instructions.