I had an issue of a printer showing up as offline even though it was most certainly online. I could ping it from the print server, and I could view the html pages for the configuration of said printer, but the print server was still listing it as offline. WTF, eh?

Then I came across a hotfix from Microsoft that says if the printer uses SNMP for certain communication that if it goes offline at any time there is a possibility that the printer will show offline even if all other communication works. The fix is as follows:

ON THE PRINT SERVER/HOST:
Open Regedit
start > run > regedit
Locate the Print key container
HKLM\SYSTEM\CurrentControlSet\Control\Print
Add a DWORD value to the print key container
Right-click and add DWORD Value
Give the DWORD key the name of SNMPLegacy
Set the SNMPLegacy key to 1
Close out of the registry editor

Now reset the print spooler service:
Start > run > services.msc
Find print spooler, right click, restart service
Test