Wandering is a big part of my mum's dementia. 2 years ago she was out the garden gate and around the village, I would often have to get in the car and go look for her. The distance she wandered got shorter - to garden gate open it check bins and back into the house. I have only been able to ease my worry and anxiety by putting a small combination lock on the gate, angry about this at first but she got used to it, at same time I moved all bins from gate so she could not climb over. At same time I put various things around the house that hopefully she would spot and stop for a while to check out/sort and tidy, as a distraction this worked well and still does[sometimes].
Now we are at the stage when she is still wandering, but only to the gate and back, for my part I have had to accept this as she is relatively safe - nothing to trip on out there. Wandering always starts around 1pm and usually goes on all afternoon and into early evening so at 4pm when it is getting dark, I lock the front door, she still wanders around the house and occasionally tries to open front door. The hardest part for me is when she takes a break from this wandering for about 4hrs in evening, then I get her into bed but some nights within an hour she is up and wandering around the house and this can go on for hours and extremely hard to ignore.
My Mum likes to wander and we have learnt that it is best not to try to stop her or try to talk her out of it as it just makes her very angry. We have got a tracker which is in her handbag and we can follow where she goes via a smartphone (before the tracker we used to follow at a distance). Also my Dad takes her out for short walks several times a day and this helps to decrease her need to wander. Sometimes just wandering up to the top of the road and coming back is enough for Mum - it seems to calm her down. I think that it is knowing that she can come and go as she pleases that seems to be the important thing for Mum.
Not sure if this helps you but you are certainly not alone in dealing with it!
I have written on a number of threads about my husband's epic wanderings. This got so bad that the SS decided to part fund him for a care home some months ago. However a combination of increased medication and three days in day care has stopped that happening.
I thought it was a thing of the past but today he is obsessed with going back to the house he lived in fifty years ago and I have had to do continuous distracting which is very wearing. I hope this is a one-off.
It is a very difficult matter to deal with and you need to get his CPN onside to calm him down with whatever it takes. You also have to keep him busy and the daycare is best for that.