Are we getting closer

We had some friends over Saturday night. Tanner did his usual ballistic barking and carrying on. Eventually, with everyone tossing him a treat he joined us in the living room and laid quietly by my chair. If our guests moved from their chairs though he started barking at them again.

What more can I do?...If I leave him in another room or put him outside he barks even more.

He is fine once the same person comes to visit after a few times....then he is gushy friendly but until he feels sure of them, he is very territorial.