Unfortunately no one can be told what fun_plug is - you have to see it for yourself.
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I have DNS-320L with latest Alt-F firmware. When I connected printer HP LaserJet 1020 I see it on status page. Driver is used Foomatic/foo2zjs-z1.
When I send test page I get nothing and on CUPS Printers page I can see "Waiting for printer to become available...".
I tried to use HP drivers, but in this case on the CUPS page I can see, that OK, but printer dont print.
How can I fix this problem?
PS Sorry for my english.