As the IT lead you check that first.
Next read from https://www.google.com/search?q=accessing+SMB+shares+across+subnets&ie=utf-8&oe=utf-8 as this is a well done subject with lots of priors.
Lesson: Not always the same thing. What is it this time?
none of my windows 10 devices can access SMB shares on a server 2012 box that is in a different subnet. We get error system error 53 the network path was not found.
our win 7 machines can access the same shares in question
the 2012 box can access a share on the win 10 machine.
all 3 firewall profiles are off on both client and server.