Finally I fixed it. Solution is weird but it works.
Do not use dhcp. Somehow it’s picking up domain name instead of using workgroup field in it’s own configuration. And it’s only visible in Web UI network info page.
Domain prefix must be set on all PC boxes. (Why?) And again I have no idea how it affects hosts list filtering.
Funny part - to have it working I must have both my PC boxes turned on. When one of them turned off, both not visible in list of available hosts. Go figure … what is it.