Hi, managed to fix the problem by adding option PPPOE_TERM_UNKNOWN_SESSIONS
to the kernel config and rebuilding/installing. In the end, using chap rather than pap auth worked. It still took a bit of time to log in (about 4-6 mins). Maybe the asus was leaving stale sessions. Even with the kernel option enabled, was unable to get pap auth working, yet the ISP's support states either should work. So maybe it's down to the ISP. Sorry for the noise.
