Originally Posted by
Mountain Trader
There is no RER stop at Terminal 1, which is where UA operates. You have to go to Terminal 2.
This is not exactly correct. There are two RER stops at CDG. There is one at Terminal Two which is walkable from some of the sub-terminals but not all.
The RER stop that is labeled Terminal 1 is near but not at Terminal 1. It is directly connected to the Terminal by the CDGVal airport driverless train service as etch5895 has indicated. You do not have to go to Terminal 2.