Questions before I buy

I have computer that cuts out from wifi networkwhenever it goes to sleep.  Need to reconnect manually every time. Believe problem is defective wifi network adaptor. Unit is too far from modem to run wired connection.  My ISP is a cable company. They suggest using WNDA 3100vs connected to cable input (like a modum) and then connect direct to computer. They say this will be equivalent of hard wiring computer so ti by passes wifi.  My question is will this approach work if there is problem with computer's network adaptor or does this bypass the adaptor so it doesn't matter if adaptor defective.