Was wifi calling turned on?
Ive encountered issues with some of the cheaper samsung A series not taking calls very well over wifi calling.
In one instance, it would not call out, either it would disconnect or not even call out at all, incoming calls appeared OK, and wifi strength/speed was good.
Tested it on my wifi with zero issues however.
I suggest you disable wifi calling and see if it behaves better?
Edit, i see you got it sorted, but keep an eye on it if the problem persists.
Ive encountered issues with some of the cheaper samsung A series not taking calls very well over wifi calling.
In one instance, it would not call out, either it would disconnect or not even call out at all, incoming calls appeared OK, and wifi strength/speed was good.
Tested it on my wifi with zero issues however.
I suggest you disable wifi calling and see if it behaves better?
Edit, i see you got it sorted, but keep an eye on it if the problem persists.