My small office (six people) upgraded to Windows 10 about four months ago, when one user was tricked into the upgrade, and the rest of us followed suit so we'd all be using the same OS. We all have Dell Optiplex 980 desktops that were purchased about five years ago. Four out of six are connected to a software server installed about nine months ago; we all connect to the internet through a switch.
Since the Windows 10 upgrade we've had nothing but headaches with our network. We have two basic issues that I have been unable to resolve:
1) Most of us cannot access each other's desktop printers, although we can all access the one printer that's networked directly through the switch. For the most part the printers are not appearing "on the server".
2) Most of us cannot access each other's documents, although there are two computers that use a very old (pre-Y2K) utility software, and those folders can be accessed by all users!
Also, not a problem but more of a symptom, is that when looking in CP Devices & Printers, only two computers show up under the Multimedia Devices area, when all six computers should be there.
I can guess there may be a group policy setting that's out of whack, but I don't know how to modify group policy or how to troubleshoot it.
I have reviewed this thread Latest networking issue caused by KB3189866 and KB3185614 and find that only two of us have one of the KBs installed (KB3189866), with no apparent connection noted between its presence and ability to access other users, since one of the two users can connect to other computers and the other user cannot.