Okay to shut modem off when I am away?
I don't see why not.
Yes, depending on your needs, you can also setup your computer so you can access it remotely too, if you leave it on while you are away.
I wouldn't unplug your cable terminals while away, but modem is safe.
I turn the power bar off to my PC after every use. It kills the modem, router, speakers (No draw while off anyway but W/E.) and monitor. (Yes, I am that cheap!!)
I haven't had an issues doing this. Just flick the switch when I want to use my PC and by the time it boots up, the modem/router had been ready for use for some time already.
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