Lo he cambiado, y sigue sin conectar (ni en adroid ni en iOS). El log da un error:
4 19:27:31 OpenWrt daemon.info xl2tpd[1632]: Enabling IPsec SAref processing for L2TP transport mode SAs
Apr 24 19:27:31 OpenWrt daemon.warn xl2tpd[1632]: IPsec SAref does not work with L2TP kernel mode yet, enabling forceuserspace=yes
Apr 24 19:27:31 OpenWrt daemon.crit xl2tpd[1632]: setsockopt recvref[30]: Protocol not available
Apr 24 19:27:31 OpenWrt daemon.info xl2tpd[1632]: Using l2tp kernel support.
Apr 24 19:27:31 OpenWrt daemon.info xl2tpd[1633]: xl2tpd version xl2tpd-1.3.1 started on OpenWrt PID:1633
Apr 24 19:27:31 OpenWrt daemon.info xl2tpd[1633]: Written by Mark Spencer, Copyright (C) 1998, Adtran, Inc.
Apr 24 19:27:31 OpenWrt daemon.info xl2tpd[1633]: Forked by Scott Balmos and David Stipp, (C) 2001
Apr 24 19:27:31 OpenWrt daemon.info xl2tpd[1633]: Inherited by Jeff McAdams, (C) 2002
Apr 24 19:27:31 OpenWrt daemon.info xl2tpd[1633]: Forked again by Xelerance (www.xelerance.com) (C) 2006
Apr 24 19:27:31 OpenWrt daemon.info xl2tpd[1633]: Listening on IP address 0.0.0.0, port 1701
Apr 24 19:27:31 OpenWrt user.info sysinit: no files found matching '/etc/strongswan.d/charon/*.conf', ignored
Apr 24 19:27:31 OpenWrt user.info sysinit: Starting strongSwan 5.1.3 IPsec [starter]...
Apr 24 19:27:31 OpenWrt authpriv.info ipsec_starter[1635]: Starting strongSwan 5.1.3 IPsec [starter]...
Apr 24 19:27:31 OpenWrt user.info sysinit: !! Your strongswan.conf contains manual plugin load options for charon.
Apr 24 19:27:31 OpenWrt authpriv.info ipsec_starter[1635]: !! Your strongswan.conf contains manual plugin load options for charon.
Apr 24 19:27:31 OpenWrt user.info sysinit: !! This is recommended for experts only, see
Apr 24 19:27:31 OpenWrt authpriv.info ipsec_starter[1635]: !! This is recommended for experts only, see
Apr 24 19:27:31 OpenWrt user.info sysinit: !! http://wiki.strongswan.org/projects/strongswan/wiki/PluginLoad
Apr 24 19:27:31 OpenWrt authpriv.info ipsec_starter[1635]: !! http://wiki.strongswan.org/projects/strongswan/wiki/PluginLoad
Apr 24 19:27:31 OpenWrt user.info sysinit: (null):0: syntax error, unexpected $end, expecting EOL []
Apr 24 19:27:31 OpenWrt authpriv.info ipsec_starter[1635]: (null):0: syntax error, unexpected $end, expecting EOL []
Apr 24 19:27:31 OpenWrt user.info sysinit: unable to start strongSwan -- fatal errors in config
Apr 24 19:27:31 OpenWrt authpriv.info ipsec_starter[1635]: unable to start strongSwan -- fatal errors in config
Mirando otra vez en la configuración, en el fichero xl2tpd.conf, se incluye auth file = /etc/xl2tpd/xl2tp-secrets. ¿Cómo es tu fichero xl2tp-secrets?