Quote Originally Posted by hcp_dk View Post
After some work from SUSE and via Forum regarding CUPS and Firewall, some spend time we found out, the print job lose lot of data. I could print from Windows out of KVM - but even here it took some time and I lost data.
Troubleshooting is a process of elimination.

In a very early post you said:
HP LaserJet 700 MFP 755 from Windows: No problem wherever in network.
Then you said:
I can print
- via USB
- via Windows in a KVM virtual box !!
- on Dell printer
- sometimes - randomly it happens
Conclusion: If you can print from Windows, then the printer is okay.

Once you realized you do have errors when you print from Windows, that suggests there is an issue with the printer.
Since hardware was new, the last weak point seems to be the printer.
Update Firmware:
Update Firmware is always a risk.
- download firmware from HP and unpack on your PC
- on your browser type IP adress of printer and go into printer.
- update firmware via LAN
After update of Firmware, the printer works very fast and fine.
That makes sense. I'm glad the new firmware resolved your issue!

BUT: the HP printers do NOT work without HPLIPS.
Printer NEED to be installed via HPLIPS.
You knew this in the beginning.

HPLIP requires that certain ports are open. You tried to open the ports but did not configure your firewall correctly. That's why it didn't work.

This demands all interfaces on internal.
No! The required ports need to be open.

Assigning an interface to the Internal zone allows all traffic. No ports are blocked. All ports are open.

The right way to do this is to assign the interface to the External zone and make sure the correct ports are open. This way your system remains protected and you can print.

After installation, interfaces might be on external again.
The print still works.
Yes, it would be a good idea to do that!

I'm glad you finally identified the problem and got your printer working. Thank you for updating this thread so others reading it will also have the solution.