It is not. The DPI is part of the main board of the printer. if you change the print head, you must change the electronics. There is no reasonable way to do what you are asking. At least not cost effectively. It would be cheaper to buy a 300dpi printer.
Depending on the type of connection you are using it could be a Main board issue or Ethernet card failing. Make sure it is a printer issue and not a problem with cabling, IP addresses or your PC before replacing any parts. (ignore pictures FixYa is grabbing the wrong ones)
Main Board ZEBRA P1004273 MAIN LOGIC 8MB XI4 SERIES New
Ethernet card ZEBRA 79501 011 KIT INT PRINT SERVER 10 100 Refurbished
