@dgl @JdeBP @lyda @ska Oh, nice. I tried to find something doing that in the net package but clearly didn't look deeply enough. That hopefully means fixing it for FreeBSD might be feasible for Go 1.26, or maybe 1.26.1.
(I was thinking it was going to need major changes which would definitely be a no-go for 1.26.)
The special case explains why my Go program worked, oops; I was assuming it used INADDR_ANY when Go is cleverer.