If I could share some info about our struggles that are similar to yours.. for the antivirus, you could ask your IT to add exceptions to the entire QB folder. We have AVG server edition and haven't had any problems.

For the NetShareGetInfo for path, two weeks ago we had the same problem & nobody could login. I ran the QB Server Manager app on the server. That fixed the problem.

As for crashing, we now have 3 pc where qb crashes every time the co. file get opened. Since we have not received a fix, a test company file has to be opened first every morning. Then close it, then open the networked company file. QB works w/o crashing. A workaround. Hope any of this will help you!