If you're in the mood to play with friends online, you should download 4p Scaled Solo for EX Quest Pack. It will help you get a better feel of the game.
With this mod, you'll be able to play in a 4-player environment with your friends as it changes monster's HP to 4 player scaling.

For instance, if you want to play with two other friends, you can do so by creating two new rooms in your game, and then connecting the three of you in the room.
Also, if you want to play with one of your friends, you can do so by simply connecting the two of you in the same room.
Now, it's possible to create a room with 4 players.