No idea why they keep sending OpenReach engineers if the xDSL link to the cabinet remains in sync at all times.
Does the Billion definitely support 1500 MTU?
Some will only do 1492 (8 bytes are used by PPP)
With those errors I would try 1492 MTU/MRU.
Is there any PPP LCP echo settings on the Billion?
Edited by j0hn83 (Tue 20-Nov-18 13:11:26)