I had have these strange problems too but they are gone, unfortunly my configurations is so complex that i do not what i have change and to the same time my provider have problems with pppoe
One change that i have do was i use other MAC adresses as before from any random to '02:BE:F5:15:67:XX' but i have no idea if this was the reason.
I use OpenWrt SNAPSHOT, r9945+40-bc85640cdc for my Easybox 904xDSL
An other problem is SQM: SQM reboot my Router (Easybox 904xDSL)
An other strange thing is
/etc/init.d/dsl_control status
show me Annex A and my dsl config are:
config dsl 'dsl'
option annex 'b'
option tone 'av'
option xfer_mode 'ptm'
option line_mode 'vdsl'I remember that as i have these problems that i use: option tone 'auto'