needs help with mouthing

I have a border collie/dane mix, 8 months old.

I'm having a hard time with mouthing, using teeth. I've had him since June, and this is one habit I can't seem to get him to break.

What have you been trying?

Does he mouth when he gets excited or overstimulated, or when he wants something, etc?

Does he know the basic commands? (sit, down, come, stay, walk nicely on lead)

Read this! Excellent!

Bite Inhibition Article

Does your dog know "leave it" and "down"? If not, train him now. If he is herding your family (nipping at legs), use a normal tone of voice and tell him "down". Reward with treat, petting, and praise, gradually omitting the treat. If you have children that he is running down, he needs to learn that the correct response to moving children is to lie down. This behavior can also be curtailed by putting a toy in his mouth and making a game out of his finding a toy and carrying it around.

If he is mouthing you to get your attention, tell him to leave it, rewarding when he takes his mouth off you. It would help if you gave him another cue to let his wishes be known. For instance, if he sat at the door if he needs to go out.

Yes, he knows all the basic commands, he's good on the leash, but could be slightly better. He's house trained as well. He seems to do it when he's excited. Like when I get home from work, right after he's done greeting nicely he turns to using his mouth with teeth.

As for the herding, he does this too. Usually will go after our pant legs as I'm walking in the house from being outside in the yard with him.

We don't have children of our own, but nephews that visit us or we take the dog there when we visit.

Thank you.