Router question

Got a friend who has a server in his house ona wireless connection. All other computer in his house are wired connections. He hosts a website on his server. If I try to get to his website from my house or any other outside location, website come right up. If we try to access it from another computer in his house, he is prompted for a username and password. Is there a setting somewhere in the router that we missed? I thought if port 80 was forwarded, that would pretty much handle it. Seems kind of weird we keep getting prompted for a username and password at his house.

You will have to forgive me if this is in the wrong forum. Been dealing with wife, youngest son and motherinlaw being deatly ill with the flu since christmas day. Brain is running low on power.

 

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