WN1000RP Wifi extender - only 1 device at a time can connect. Is this normal?

I bought the WN1000rp extender for my small business, the building I'm in has wifi but it is weak near my office. My suitemate and I tried setting it up the other day and only one of us at a time can connect. All devices can Find the network, but only 1 device at a time wil work with it. Is this normal? If so, why isn't this better communicated to people when purchasing? Because I bought the range extender from a 3rd party it can't be returned so I've lost that money unless there is a solution.