6 months old - sounds like teething to me. A couple of things you could try - take an old dishcloth, wet it and tie a knot in it then freeze it. See if he will chew on that. I have heard of people using chicken broth instead of water to make it even more appealing.

It sounds like you are doing all the right things - No Bite commands, time outs, etc. Have you tried the ouch method. If he starts biting you say ouch in a high pitched voice and walk away. There are differing opinions about this approach, however, some trainers say it trains bite inhabition and others say it will cause the pup to think "oh they are excited too - they must like this". It is kind of up to you to find out what works best for your pup.

When Leo was younger - the ouch method worked not at all. What worked for me (and it took several months) was to remove myself and time outs in the crate. Plus of course - lots of chew toys.

Welcome to pet talk by the way! It is always nice to see new people stopping by. Hope you visit often and we would love to see pictures of your pup.