In time past I could attach to my 5N using the command smb://Drobo5N/. Then something happened in some update about 6 months ago and this no longer works. I have to use the IP address in place of the name. Not particularly a problem for me as my router always assigns the same IP address to the Drobo, but it would be nice if name support was reinstated.
I believe this is a local DNS issue and not a Drobo issue. DNS is the equivalent of a phone book…translating names into addresses. Assuming your router is maintaining your local DNS, have you recently changed or updated the software?
You might also try flushing your computer’s DNS cache and let it refresh itself. If you’re using Windows you can open a command window and enter “ipconfig /flushdns”. I don’t know about other OS commands.
I had this same issue and I contacted support, they tried to blame everything but the drobo firmware update. I changed the name of the drobo and this helped for a few days however it has reverted back to the same issue and for certain shares its easier to use the \ip\share option.
You could email drobo support and quote ref 161218-000002 as having the exact same issue.
As you say worked fine until the last firmware update and suddenly stopped.