Digital - forget what everyone (and I mean everyone) has said to you, and take some time (alone)to think about these questions:
Why do you think ds is waking up? eg is he hungry, does he need human contact/assurance, habit? etc etc
If you think you know what is getting in the way of ds's sleep, how would you like to tackle it?
If you don't know what is getting in the way of ds's sleep, how would you like to tackle it?
Also, has your ds slept ok previously? If yes, has anything changed? Illness? Teething? Has there been a disruption in your lives (have you started work again etc)? The hot weather?
My advice would be, however you choose to tackle it, you need to make a plan and stick to it for at least a week. Don't jump from one 'solution' to another (I've been guilty of this and it doesn't work.)
When you are in the situation you are in it is hard to see the wood through the tree's, which is why I suggest you take some time and thought over what you do.
If we can be of any help, just shout. Sleep training can be very draining.
You will get there