Trouble with File Sharing After VLAN Changes – What Am I Missing?

There's also the question of how the server's internet access restriction works. Is it just behind a firewall that only allows certain traffic? If no other apps can reach the internet from the server, check how the VLAN is set up and what rules are in place. Also, try accessing the server using its DNS name instead of the IP to rule out any name resolution issues. If all else fails, reverting back to the original setup might help identify the problem.

I get that you want to secure the server, but double-check your VLAN configuration. You mentioned it's a Layer 2 switch, which shouldn't normally block traffic between devices on the same VLAN. Also, ensure that the firewall rules on the server are correctly configured and that you're using solid IP routing. Sometimes the firewall profiles or rules can block shared folder access unexpectedly.

It sounds like you're on the right track troubleshooting this. Since you can ping the server from the PCs, they are communicating at some basic level. Have you tried running Wireshark on both the server and one of the PCs to monitor if the file share requests are even reaching the server? That might give you insight into where the breakdown is happening.