Windows Access Problems

I am having issues connecting to my Drobo 5N from Windows 7 and Windows 8.1 computers. I have tried from computers joined to a domain, and from standalone computers. Interestingly enough, I can access my Drobo FS from Windows 7 and Windows 8.1 computers. I can access both devices without trouble from my Macs.

Any ideas why this may be and how I can fix it?

Thanks!