Yes, I've always been charged for using the in-room internet at CP, Rio, Rincon. The charge is between $12.99 and $14.99 per 24 hour period. So if you don't need it when you first arrive, don't set it up as the 24 hours start at your first connection. Also, if you connect your laptop and a tablet, you pay for each. I'm Diamond level and the internet fee has never been comped even though my room was comped.
CP has a Starbucks just before you get to the Augustus tower elevators, I think they have free wi-fi available. It would be really convenient if staying in the Augustus tower. I prefer to pay the fee than carry my laptop around. Only once did a CET property not let me use my points to pay the internet fee.
Update: According to LVA visitor guide for free wi-fi spots Starbucks wi-fi is free only if you have a Starbucks card(gift card?) you've registered or you are with T-mobile.
LVA visitor guide lists the "Munch Bar" at CP as having free wi-fi no special conditions listed
I'd check with the Munch Bar for hours it is open.
