FTTC - Is it necessary to leave Modem/Router on 24/7?

[#1]

I am happy with my recently installed FTTC service, except one thing - leaving the modem/router on 24/7 as advised in the setup guide. Is this necessary? What will be the result of overnight switch offs?
I never left my ADSL kit on overnight or when not in use for extended periods, and I never noticed any issues with speeds.
I admit, I am a bit of a green freek when it comes to energy management. Yes the impact on my bill will not be that big, but multiply by 10s or 100s of thousands of users - over a year the power waste becomes significant.
If the DLM system can't be set up to manage a regular pattern of overnight switch offs, it is a very poor show!
DJ

[#2]

Just leave the modem on 24/7 then turn the router off.
Router is just for connecting your network to modem if your not using at night turn off, leave modem on.
Connection stays up no DLM.

[#3]

Will it stay up though?
Sure the modem's connection won't drop, but there will be PPP drop.
Either way, turning it off once per day is unlikely to cause a problem, and even if it does, you can reverse the process in short order.

[#4]

Bravo sir, got me there.
Yeah PPP session will more than likely drop, don't think the modem holds a memory of the log in details.

[#5]

The 24/7 advice for ADSL was because, simply, that the DLM system couldn't "be set up to manage a regular pattern of overnight switch offs", and could be defined as "a very poor show! " The real problem is that you, as the person who turns the kit off, have no idea about what conditions the line has seen autonomously, and whether the combined effect could inadvertantly trigger DLM actions - even if your manual actions alone wouldn't have any effect.
However... that advice applied to DLM that sat in the BT Wholesale equipment.
With FTTC, the management performed by DLM is entirely within Openreach's equipment, and appears to be different. Reports so far seem to show that things recover faster - but that speeds do sometimes drop for no obvious reason too. Interleaving has also been both applied and removed with no obvious triggering reason.
We can probably say that no-one knows whether the 24/7 advice is a necessity for FTTC, but it is probably very safe to say that 24/7 is NOT detrimental.