We've had to deal with them constantly, especially around our front door and back deck, but we kept trying different things. If I had read this brown paper bag trick on a message board, I would have ignored it, but we did it, and it has virtually eliminated the issue at our front door, and significantly reduced them on our deck.
Try the brown paper bag trick. It is so cheap to try, and easy to do, that most don't try it. If my wife had not done the work on it, I never would have tried it but for us, it worked. There are actually fake hornet nests you can buy, but this has worked for us.
Knock down current wasp nests.
Hang stuffed brown paper bag nearby. Also hang one near your grill if you have to deal with them there.
Repeat next season or when bag gets blown off.