Amped Wireless High Power Plug-in Range Extender

I bought one of these from the local Costco several years ago (3-4?). It was intended to boost the range downstairs because the main router/modem is upstairs around the corner. It works well. If you are anticipating using it in an area that needs a particularly high signal (i.e. garage, outside, etc.) it may, or may not, do the trick.

Was just wondering if anybody knows wether the external detachable antenna is for the uplink side (to the router), or for the relay side (extended signal) Thanks

I looked into the User Guide, and alas, it doesn’t say.