i just had this autostart problem aswell some days ago. its related to changings in the most linux distros from initd to systemd. it took me two hours or something, but finally it worked:
i created 4 files:
create files in /etc/systemd/system and link them to /etc/systemd/system/multi-user.target.wants
/etc/systemd/system/hfaxd.service
[Unit]
Description = Hylafax hfaxd
#ConditionPathExists = /etc/iaxmodem/ttyIAX
#Requires = asterisk.service
#After = asterisk.service
[Service]
#User=root
#Group=root
Type = forking
ExecStart = /usr/sbin/hfaxd -i hylafax
[Install]
WantedBy=multi-user.target
/etc/systemd/system/faxq.service
[Unit]
Description = faxq
[Service]
Type = forking
ExecStart = /usr/sbin/faxq
[Install]
WantedBy=multi-user.target
/etc/systemd/system/faxgetty.service
[Unit]
Description = faxgetty
#ConditionPathExists = /etc/faxgetty/ttyIAX0
#Requires = asterisk.service
#After = asterisk.service
[Service]
Type = simple
Restart=always
RestartSec=30
ExecStart = /usr/sbin/faxgetty ttyIAX0
[Install]
WantedBy=multi-user.target
/etc/systemd/system/iaxmodem.service
[Unit]
Description = IAXmodem for /dev/ttyIAX
#ConditionPathExists = /etc/iaxmodem/ttyIAX
#Requires = asterisk.service
#After = asterisk.service
[Service]
Type = simple
Restart=always
RestartSec=30
ExecStart = /usr/local/sbin/iaxmodem ttyIAX0
[Install]
WantedBy=multi-user.target
reboot - services shoud run as expected.