If your printer shows offline, there could be numerous things to cause it. To get it back online, follow these steps.
Power
Check to see if the printer is powered on. Often the printer’s power cord gets loose from the back of the printer or power outlet and will cause the printer to show offline.
Data Cable
A loose parallel, Ethernet, or USB data cable will also cause the printer to show offline. If this is the case, shut off the printer and reconnect the data cable properly. Once the parallel, Ethernet or USB data cable is reconnected, return power to the printer and check to see if the printer shows offline.
Drivers
Is the D, the DN, the T, and the TN able to use the same drivers? Sometimes the same drivers will function normally but don’t always count on it so if you are swapping printers while one is under repair, add the correct drivers to print without issues.
Duplicates
If you are not careful, printers can be duplicated causing issues so be sure to check the Devices and Printers section to see if ‘copy’ is amended to a printer name. Another form is one printer for each network account user that had signed in.
IP Conflict
If a device on the network is using the IP address on their machine, this will cause an IP conflict. I like to use 1-10 for routers, 11-20 for servers and 21-30 for printers, and 31-100 for restricted Internet access. Now if someone tries to use the printer’s IP Address as a static address to circumvent the block, this will cause issues until it is corrected.
Ports
If someone forgot to give the network printer a static IP Address, you may find this has changed so make sure that the IP Address in Devices and Printers matches the one in the printer. Also, If a printer has moved from LPT1 (parallel) to USB001 (USB), this will cause issues as well.
Sharing
If the shared printed on a PC got reinstalled, you will need to sync your connection once more for all guests.
