With the past update to Windows SMBv1 was disabled, which means the old style network browser no longer works. For a system to show up in the network browser now, it must support WS-Discovery.
I’ve forked a version of Netgear’s wsdd2 service, and got it working on my Rockstor box.
You can find it here: https://github.com/cryolithic/wsdd2
Just clone, make, make install and start the service.