Is there ANY hope of DDog2 ever learning?!

[TheFlandersPigeonMurderer]

He's a 4yo working cocker who we've had since he was 8 weeks old.
He's treated exactly the same as DDogs1&3 and we are firm with our boundaries.
DDogs are not allowed upstairs or on the furniture including the dining table
All well and good you might think, except that DDog2 simply refuses to "get it". He will run up the stairs, we will shout him to come down, he will look bemused (as if we've never communicated that rule before in his life) and return downstairs. Same goes with the furniture
This is constant and it seems that nothing we do has any effect. I'd happily say that he had some sort of issue it's that bad, but he can wait for food, has impeccable recall and will wait at roads etc. so it's not the case that he can't remember commands.
It's got to the stage where it's really starting to get me down and I'm at my wits end. DDogs 1&3 manage it perfectly so why not DDog2

Prevent behaviour you don't want. Stair gates.
Focus on rewarding what you do want. So lying quietly in bed.

We do have a stair gate wolfie but so determined is he that he will paw it open (DH has spent hours devising increasingly fiendish ways of keeping it shut) One of his favourite things is to lie on the dining table when we're out so it's impossible to police (he'll see the car pull up and be lying on his bed when we open the door )
The only option I can see is to leave him in a cage, but that hasn't gone any way to actually solving the problem.

Is it that he wants to be with you? Is he bored? (Obviously a bright boy!)

He wants to be with DH 24/7, stood up on his leg and staring devotedly into his eyes while shooting daggers at the others who may try and share his affection
It's noticeably better when he's tired (so shattered he struggles to lift his head) but as a working cocker, proper tired is either a day in the field or at least 3 hours walk which is not sustainable on a daily basis.
We recently put them in kennels for 10 days while we were away and made a conscious effort on their return to stop him doing rapey leg jumping up, working on the basis that his stay in kennels will have broken the association. Three weeks later and while things have improved he's still trying valiantly, despite having no positive feedback whatsoever

Do you think there is an element of separation anxiety? Watching for you return from the dining table etc

How much mental stimulation is he getting? Getting them really using their brains is much more effective (and more convenient) for tiring them out than providing ever increasing amounts of exercise. There's a couple of FB groups (Canine Enrichment and Beyond the Bowl) that are great for getting ideas from.

If he's always on the go at home another thing to look into is teaching him an off switch. Settling down in the house isn't always something that comes naturally to some dogs but it can be taught very successfully. Kikopup on YouTube has a good series of videos called 'Capturing Calmness' () which is really good.

Impulse control exercises can also have a really positive effect on a dog's behaviour in general. The is a really good place to start.

I've got a 4 yr old working cocker, and he's a bloody nightmare. He's had a bad leg recently, so vet said reduced exercise, no stairs and no getting on and off furniture. I literally was borderline insane after 4 days of it, we had stairgates everywhere and the dog hasn't had nearly as much rest as he should have. They are very stubborn souls, and mine has chronic separation anxiety. If you find the answer, please let me know . It's a darned good job he's as cute as he is.

Not separation anxiety no, all three are happy to be left in the house, car or anywhere we happen to be staying (e.g. at my DM's) so long as there are at least two of them there (they all have a morbid fear of missing out so we rarely separate them) He lies on the dining table, in the sun, watching the world go by and frightening the tweety birds on the feeder, no signs of anxiety at all
I would say he could be bored but he has no truck with games or anything like that. We tried a Kong and a Buster Ball in the past and he just doesn't get it, probably not helped by the fact he's supremely unmotivated by food.
The thing is he's so bloody determined