First off wlp2s0
is within the new naming convention that Arch Linux is using; wlan0
is the older (and more conventional) naming convention. They've changed as the new convention tells you more about the connection.
I'm not a massive fan, but I understand their reasoning.
I unfortunately cannot help, at least not directly.
You may wish to check the ArchWiki Wireless Setup
It's a little out dated with some of the naming conventions. However, it should point you in the right direction.