Separation anxiety 11 month old whippet

[Losingmymind85]

So DDog is a good boy. Loving, decent recall etc but we're having real issues with house based separation anxiety.
If we go out, he's completely fine. Will settle in his bed and doze (we have a camera so he's 100% sleeping). No barking, no stress etc.
If we're IN the house, it's a totally different story. He starts whining if one of us leaves the room, gets up and follows. Will howl at the bottom of the stairs even if one of us is downstairs with him.
He was so great at bedtime and would go happily into his crate from 10-7 . In the last three weeks, he's been refusing to sleep and crying/howling/whippet screaming for up to an hour at bedtime, doing the same if he wakes in the night and then up for the day at 6.
Everyone is exhausted.
We've taken him out of the crate and how he has free movement and 2x beds in the dining room but he cannot settle.
I can't have him upstairs in our bedroom because there is zero chance he'll settle if he's not in the bed with us and i won't sleep getting kicked all night.
We've tried light on/off, white noise, pyjamas, blocking out light. Nothing works.
Does anyone have any advice on how to approach this? He's such a sweet boy and obviously wants to be with the pack but it's not a practical solution.

Can he not have his bed outside your room, with a baby gate so he can still hear and smell you?

@fieldsofbutterflies we thought about him being on the landing but I'm up a lot during the night so will disturb him. Honestly, I think the howling would be worse if he was on one side of the door and we were on the other and he couldn't get to us.

I’d try him in your room on a bed , if you keep putting him back on his bed he will get the message - it’s probably worth a try and he’s always got the option to go back downstairs if he wants . Ours very often moves from our room to downstairs in the middle of the night .