4 yr old not making friends at nursery

[FagAshLil]

Ds started school nursery in september, he'd been at a lovely pre-school for a year before that.
At pre-school he had a lot of friends who have mostly gone on to infants this year.
He's really struggling to make new friends at nursery, says no one plays with him and he just walks around on his own. It's breaking my heart to think of him on his own for 3 hours every day
What if anything can I do to help him make friends?
I'm going to speak to his teacher tomorrow to see if she can encourage him to play with others more but is there anything I should be doing to encourage him myself?

id go in and watch for a session to see for myself then you can decide for sure?

ds is kind of the same. Last year he had 2 friends who went to school and he hasnt really bonded with any of the new children that started. He is quite independent though and will play by himself in the different areas of the nursery - he just doesnt interact much with the other kids. He is getting speech therapy just now too so his unclear speech may be an issue as well. It does make you sad when you think they are on their own especially when you know thay can be sociable at other times.

I spoke to one of the TA's today she said he does he's own thing and seems happy.
Not sure if we're allowed to go in but will ask thanks Nordic.
That's exactly it Seona, He's a social little thing most of the time which makes it harder for me to understand I guess.
I think he also has the opposite problem in terms of speech, he's the one of the oldest and has a lot of older friends so I think he struggles with people he can't understand properly.
Thank you both, think I'll speak to he's teacher and see what she suggests and just keep up the friendships he does have.

Can you not arrange to have a couple of the kids from his group to come over to play with him?