Boost wireless signal from one building to another.

Odd situation here. Our offices sit in two different buildings, about 25 feet from each other (if that). Our Internet and telephone connection are via Charter. A wireless router sits in one building, and the phones and Internet connection are used in the other building.

Every afternoon, and I do mean every afternoon, the phones and computers furthest from the building in which the router sits lose connection.

I’m thinking add a booster in our building. Am I thinking correctly?

We don’t own either building and so are very limited as to what we can do with things. We haven’t the funds to hardwire.
The router in place is:
Linksys WRT 300N Wireless-N Broadband Router

Handy dandy tips, hints, suggestions will be entertained and rewarded. Thanks folks!

etu