PPPOE authentication issue
Just tore my hair out a little bit over this. If you initially install pfSense with a typo or an otherwise incorrect PPPOE password, apparently no amount of editing the interface or modifying the password in the PPP section of Assign Interfaces or the WAN interface editing page will change it to the updated password. The behavior persisted across reboots, deleting/re-adding the interface and PPP, etc.
Once I restored to default settings and made sure to type it correctly (no other changes to the system, mind you), it instantly worked perfectly.
Can't replicate that. Set password to password on interfaces.php for the interface, saved, applied changes.
# grep password /var/etc/mpd_opt1.conf set auth password password
Changed password on interfaces.php to asdfasdf, save, apply changes.
# grep password /var/etc/mpd_opt1.conf set auth password asdfasdf
Same if changed under Interfaces>assign, PPPs tab. Works fine. Also connects fine where I change the password PPPoE server side.
The mpd_<interface>.conf file in /var/etc/ is the only location that resides on a running system. The data that creates that file is in your config.xml. If there's some scenario you can replicate, please post back info.</interface>