HP OfficeJet 7500A is not supported on Linux
As stated by CUPS
http://www.openprinting.org/printers/manufacturer/HP
and as stated by HP into HPLIP site.
https://developers.hp.com/hp-linux-imaging-and-printing/supported_devices/index
(I am assuming that this is the printer you are talking about)
https://support.hp.com/us-en/product/HP-Officejet-7500A-Wide-Format-e-All-in-One-Printer-series---E910/4083647/model/4083648
If you currently are using in any way this printer into linux, you should become able to reproduce it on NethServer, but i don’t know how.
I hope this will help you…
As stated by HP, printer supports HP PCL 3 GUI
https://support.hp.com/us-en/product/hp-officejet-7500a-wide-format-e-all-in-one-printer-series-e910/4083647/model/4083648/document/c02283601
So maybe this driver
http://www.openprinting.org/driver/pcl3
could be used/adapted for let your printer work, but i am not sure about that