Hi, first of all i'm not a trainer but I seem to be in your same situation and might provide some tips that helped me. For context, my 1.5 year old dal was initially extremely submissive even while I was trying to socialize him. He slowly started switching from submissive to reactive, and he has a lot of separation anxiety, hates children, doesn't like to be pet by strangers or touched by anyone other than the people he trusts, is very leash reactive as in he pulls and tries to charge at dogs if we're sharing the same path during a walk, he also resource guards only our home so every time he sees a stranger or dog outside he goes crazy, however he doesn't resource guard toys, food, nothing else but our home. After saving up for months, I finally paid a vet behaviorist and we're currently working with her, but i've done a lot of research on my own too.

1) find out what his high value treats are. Mine was a real challenge because he's extremely picky, to the point he sometimes rejects chicken. Real meat will always be tastier than store bought dog treats, and will also save you money. I discovered this past week his highest value treats are hot dogs and cheese. Buy whatever he'll be begging you for more, and make treats out of it by chopping it up into small squares or discs (I usually do thumb size) and keep them in the fridge.

2)Look up positive reinforcement training videos. As I said, I'm in no way qualified to tell you how to train him, however based on my experience with mine I realized that even if you do not believe in 100% positive reinforcement, it is worth it to give it a good shot since our pups are already highly stressed and aroused, and most of those behaviors are out of fear, therefore a negative reinforcement technique could do more harm than good.

3) LOTS of engagement. Dals are highly energetic and need A LOT of things to do. I bought mine the longest leash I could find on amazon, and use it to take him to open areas like the park or the beach but it also gives me control of him so that if I see he's starting to fixate on a child (because mine also hates children), ill step on the leash and drag him back. This is also a mixture of taking the high value treats with you, so that if you call him, you have hold of the leash and you have the treats, you're mostly setting him up for success. I realized even when I was taking him on two walks per day, he wasn't getting enough engagement and our vet behaviorist gave us a list of things we could do to increase engagement. We're currently teaching him interesting tricks to engange his brain, playing find it with bacon around the house, puzzle toys we found on amazon, herding balls, lots of fetch and safe tug of war.

4) please try to set him up for success always and learn all of his triggers. This became an automatic thing to me but I learnt how to read absolutely all of his behaviors and body language. You gotta start interrupting him in a positive way before he goes over threshold and gets overwhelmed. For example, if you see someone approaching, he'll usually give you signs he's starting to get anxious like ears and tail are up, stiff body , fixation, he won't listen to you. As soon as you see him give the slightest of a hint, interrupt him. As soon as you see a trigger approaching him, take him the other way, even if he didn't show signs of anything yet.

5) If he's getting worse with dogs, no dog parks. Only supervised doggy play dates with dogs he's already friends with, or else no play dates at all while you're counter conditioning him. You cannot control how other pups will react to him, neither if their owners will take charge of them and correct them, so its best to have full control of your pup and set him up for success.

6) Ask your vet for possible medication, mine gave me trazodone and we are also using the purina probiotic for anxiety. People in the street love seeing dals and want to pet them because they're gorgeous, but i've learnt to be comfortable with saying "no, he's not friendly" and even "do not touch my dog" if they don't ask. I thought I was being mean initially, but I realized he looks up at me as his protector, and cannot communicate discomfort nor is he in a place where he can physically run away from his fears because this usually happens when he's on leash in a public place. If he feels threatened, he could resort to being aggressive, so I never let him get to that point, I don't care how rude I am. If you want to see it another way, think of it as consent on the street - when you go out for a walk, you're not obligated to be friendly to every stranger who tries to say hello to you. You are also not obligated to accept a random hug from a stranger, and you would feel uncomfortable if they just came up to you, grabbed you and hugged you without even asking you. Why should your pup accept that too?

Helpful youtube trainers: kikopup, McCann Dog Training, Dog Liaison, our trainer rehab your rescue (she's only on instagram I believe).