9 yr old DS, doesn’t let me talk to DH

Give it a few years and he won't be bothered about talking to either of you. They grow out of this excited for attention phase. And it definitely sounds like he wants more attention and time with dh .
You only get them for a few short years then they get to older teen stage and you will be desperate for attention from them.

He is 9 so can keep up with a convo. Involve your son in the talk. Keep it to subjects he can contribute to. Once he is in bed, then you can have your time with your partner.
Your DS needs your attention and that is what your husband is seeing and you are not.

I can understand your frustration but DS will probably be like most teenagers in a few years time, and you might wish he would come out of his room to talk to you instead of only appearing at mealtimes, and having to be conjoled into answering you.
Now that most of DC are adults I wish that I had had more patience for their talking when they were actually excited to see us after work but at the time it's so hard to fit everything that needs to be done in to those few hours before bedtime. When they were in bed I was too tired to remember what we needed to talk about.

DS jumps in with something trivial

I think this is the problem you have here. You don’t value what your child wants to say. It might be trivial to you, but it is not trivial to him.

If you don’t listen when he wants to tell you the small stuff then he won’t be coming to you with any of the big stuff, and that you will sorely regret.

My take on this is different. Why is your husband not giving his undivided attention to your son? If he only sees his kid for an hour or so, why is he watching TV? During dinner - surely you have family chats that include kids?

I get that if Dh just sits there, you talk to him but my assumption would be that once Dh is home he takes active interest in your child, if he doesn't no wonder your kid keeps pestering him.

in our household, logistics and important chats are usually kept until after kids are in bed as I can't handle them bring interrupted all the time and it's easier that way.

OP, have you had a direct conversation about this when the kids aren't in bed? No accusations, just a discussion about how the two of you can work together to teach your DS this social skill and make sure both of you feel properly in-touch with each other.

One possibility to consider... you said if you're not trying to talk to DH then it ends up with DS walking away or sitting there reading a book while DH watches TV. Is it possible that DS finds it hard to get and keep his dad's attention in the evening and he's unconsciously trying to sort of capitalize on you having DH talking and not distracted by a screen? In addition to talking about specific strategies for responding to the interrupting in the moment I might ask your DH to set aside some focused, screen-free time every night for the two of them as part of DS's routine and see if that helps.

I've read all your updates and you seem to ignore something people keep saying!
i have an adhd/asd 12yr old. She does this constantly when me and my husband trying to have an adult conversation or even a conversation. We've tried various methods to manage it, ours still doesn't change it. She's adhd, it is an adhd behaviour.
your argumentative and defensive responses also suggest adhd too (always have to win behaviour, I know an adhd person who got sacked because of this)
I'm fully expecting you to come at me with a argumentative response and that's ok, I'll just ignore you. hopefully my points will make you think

Teach your kid some manners and tell your dh to stop being a prick too.

Wow lovely patronising household you have there. 🤣

Yes, this is a husband problem. Better to fix it soon because a kid constantly interrupting adult conversation is likely to be very annoying to your friends. And at that age your son is old enough to be told it's bad manners.

I had it the other week when I visited friends. Their soon is 9, too. He talked constantly. I'm not going back to their house anytime soon.

its also so true that children’s priorities are different to ours. They will genuinely believe that what they have to say about Minecraft/Horrid Henry/some YouTuber is important and fascinating and a parental discussion about work/weekend plans is trivial and boring.

Well you were the one who said 10 minutes? So we can only respond to information you have given. That's why I thought you could wait until kids were in bed. If it's a 2 minute conversation then that's different and it should be your DH telling your son not to interrupt. Also, he ought to spend some time with his son because these interruptions are a cry for attention. If your DH tells your son "hang on, I'm talking to your mum. You know we don't interrupt when people speak. Go to your room and wait and I'll be right there when I'm finished speaking to your mum." Then everyone will be treated respectfully, you included, and DS knows not to interrupt but is assured of having his dad's attention If he waits.

The situation sounds exasperating. My son has ADHD & autism When he was your son’s age, constantly interrupted me when I spoke to anyone. It made life quite difficult. I was v envious of people who could have a brief uninterrupted chat with another adult! He improved a lot but still as a teenager finds it hard to control his impulses. It might help to chat to your son after school and explicitly tell him some rules about conversation - you take turns, listen while the other person is talking, and don’t interrupt when two people are talking to each other. You could practice using a signal like arm tapping or a raised finger as pp have suggested, so he knows you understand he wants to speak. Also talk to your son about what he’d like to happen when his dad gets home in terms off attention. Would it help if daddy had a 1-1 bedtime chat with him every night? Talk to your husband about this and ask him to get on board and point out that it’s teaching your child manners in the same way you both expect him to say please and thank you. However, if your husband really does enjoy having two people competing for his attention and won’t get on board, then you have, as they say, a dh problem not a ds problem. By the way, I guess your other child/children don’t do this?

Your DH is being very disrespectful to you by allowing your son to interrupt your conversations like this. Rather than addressing it at the time with your DH and in front of your son, have you discussed it separately?

The dynamic in our family is that we save longer important adult conversations for when the children are in bed.
That being said my DH is very strict on manners and will not have a child interrupting a conversation. But you seem to want an in-depth private conversation with your DH while your DS is there even though he will soon be in bed and you will get to have your husband's undivided attention. He comes home late and your son is excited to have him home. He shouldn't interrupt but you seem quite immature being in competition with your son for DH's attention. Maybe you ought to have a hard look at yourself?

We had a system where my DC took my hand if they wanted to speak to me. This let me know they wanted to talk. If my convo was going to be long(ish) with the person I was already talking to I would quietly say to them, ‘come back in 5 minutes’. If there was going to be a break in the conversation sooner, I’d touch their hand back to let them know I knew they were waiting, and then would revert to them as soon as I naturally could.
They knew in an emergency to just interrupt!

Kids don’t instinctively know how to navigate ‘busy’ adults, think that everything they have to say is important, and need our help rather than a bland ‘don’t interrupt’ instruction which leaves them nowhere.

I'd have walked out if I was your dh, abusive telling him to put his hand up who put you in charge?

Ofcourse you can but since you're an adult and hopefully more patient than a child you could let your child have his dad's attention when he gets home at 7:30. At 9 he'll be in bed soon anyway and you will have your DH to yourself. 🤷‍♀️

Have you taught your DS how to approach you if you are talking to someone?