Adobe Reader saying all PDFs are corrupted, when accessing files over SonicWall VPN

We had this issues and banged our heads against it for a couple days. We would get all sorts of errors when trying to open the PDF files on a network share, and when we could get them open, we couldn't save over the top of them files and would get an error saying the network name cannot be found, or the network location is no longer available. We looked at everything from Adobe, to MTU settings, to our ISP. I was poking around in the SonicWall checking the VPN connections, and I tried turning off content filtering. No change, so I tried turning off the Gateway AV. Success!!! The users could open and save, without any issues. Some trial and error testing narrowed it down to the CIFS/Netbios setting in the Gateway AV settings. This helps block ransomware/cryptolocker so I won't leave it off forever, but tomorrow I am going to call Sonicwall to get the skinny on what we need to do to properly fix this

TL;DR  If you are getting a bunch of weird issues accessing files and folders over VPN, disable CIFS/Netbios in the Gateway Anti Virus section.

I will update when I get the rest of the fix figured out.

uncheck CIFS/Netbios