Shall I turn power to router off when go on holidays?

[#1]

When go on holidays, shall I turn-off the power (plug on wall) to router?  I read conflicting answers on Google search, so I thought to use this forum.  Thanks

[#2]

I would follow the normal safety procedure if away for an extended period and unplug or switch off at the mains all non essential items - essential being items such as fridge or freezer and, depending on the time of year, perhaps the central heating system

[#3]

Hi 'plususer', and welcome to the forum !  

I am on an old 20CN ADSL exchange and my modem has a good connection with the exchange.
I used to find that switching off the modem and leaving it disconnected for a week would cause my BT line profile speed to halve (despite still having full modem sync speed), which could then take up to two months to fully recover, or would require Plusnet to place an order on BT to get my line reset.
Having repeated this sorry scenario several times, I now leave my modem connected at all times, and haven't had a problem since.
I now have a battery backup mains uninterruptable power supply feeding my modem, so my connection stays up during storms, mains voltage sags, and power-cuts (as long as they don't exceed about three hours !).
The only time my modem gets switched off or rebooted is after I've done a firmware upgrade.  

If you are on a 20CN "up-to" 7.15Mbps ADSL exchange, then my advice would be to leave the equipment switched ON at all times,
otherwise 21CN ADSL2 or FTTC connections are likely to be better at recovering than the older ADSL, in which case follow 'Oldjim's advice.

[#4]

Thanks.  How do I know if I have 20CN or 21CN?