I started a thread on it here (dont want to hijack) and its interesting that you were able to just get it working. I also found an old thread re PAP, Chap, Chap-v2, etc setup that didnt seem to help: old_thread
I know you havent posted similar errors, just wondering if you encountered the same at any point? Have you tried setup with the wizard, or just pasting config files direct?
Jan 16 17:51:37 ubnt pppd[1314]: Modem hangup Jan 16 17:51:37 ubnt pppd[1314]: Connection terminated: no multilink. Jan 16 17:51:31 ubnt pppd[1314]: CHAP authentication failed Jan 16 17:51:29 ubnt pppd[1314]: Connect: ppp0 <--> eth0.201