These 6-hour BT programmes of work...

[Bill]

Definitive answer from support.

For FTTC, power down the router as it's that which is authenticating.

That's what I thought, thanks Rik

However, it will do no harm to power down both.

Provided your line hasn't got noisier and you end up with a lower sync... that's why I don't like powering modems down

[Rik]

Though you do lose your LAN, so if you have any attached devices, eg printers, they become unavailable.

[Bill]

True... OK, if I think I'll need the LAN I'll pull the Ethernet cable out of the modem instead, that should fix it

[Rik]

 

[esh]

As you all seem to have concluded, indeed if only PPPoE goes down then just reset the connection from the router side.