As SMB, your IT will intervene when you request him. How many times did you contacted your IT for a slow internet issue, of slow files opening and when your IT may intervene he doesn't notice anything.
The main issue is that when your issues are comming there is no monitoring of your Network or Server, therefore it becomes complicate to find what is the issue unless the your IT is available when the issue is happening.
Therefore I place on network, micro computers (Raspberry, credit card format) with monitoring system. Those micro computers can monitor the main components of your network displaying their availability and showing with graph what could be the issue. Like for instance, your internet BW is full, your server harddisk available space is drastically decreasing, the memory available is pretty low.