emmerich
Last ditch effort I tried it and sets connection Do from terminal
Sorry I forgot about the connection setting.

1 lpinfo -v should see something like this for your RX520 (direct usb://ZP/LazerJet%20MFP?serial=42)
so it would look like this ( lpadmin -p Epson_Stylus_Photo_RX520 -v usb://ZP/LazerJet%20MFP?serial=42)
(Example)

2 add that line to the end of this and hit enter (lpadmin -p Epson_Stylus_Photo_RX520 -v )
3 should have changed the connection for the Epson_Stylus_Photo_RX520 printer
we should be connected to printer if all went well.
4 test
If you dont show your printer in 1 then we have deeper issues.

Note This is a follow up providing you didnt change your previous settings in previous post
meant to be done along with it.

Thanks for doing that

      emmerich Does lsusb show it connected
      Also I would try uninstalling Sane it can cause issues with some printers.

      Makes sense why it cant auto detect your printer one Line away from working sheesh

      Note Just thinking sudo scanimage -L if it shows addy for printer might be able to use it you said scanner
      was working

      If this doesnt yield results am out of ideas for moment maybe somebody has another idea.

          Axios If this doesnt yield results am out of ideas for moment maybe somebody has another idea.

          manually map ip address in printer dialogue is all I got. force solus to see it.
          see a lot of this no autodetect lately--I can't even begin to know what that is all about. maybe you are right too many backends (sane) installed?

            Axios the sudo scanimage -L shows the scanner :
            But I do not understand what to do wthit the description of the device.

              Axios in adtion the answer with lsub with the detection of the printer

                  emmerich Use this command in the previous post and see if it works (It wont dork anything)
                  lpadmin -p Epson_Stylus_Photo_RX520 -v epson2:libusb:001:005

                  Something software wise is keeping it from being seen its seeing scanner fine

                  I think if the above does not work uninstall sane -shutdown-unplug printer
                  when booted up fully plug printer back in and try to add printer like normal.

                  What we did was set it up manual but without the connection info it does not know where to send it.
                  thats why when you print test it prints a loop with those 2 notifications.

                  I know linux had bug issues with sane keeping printer from detection just process of elimination
                  If all that fails I am kinda in the dark but at least we know whats happening
                  and maybe Mods-Dev have a answer.
                  Its just I dont know all the deep inner workings of linux.

                  Let us know what happens

                  Edit- I was just looking you might try setting up a new printer using the pm 750 driver worth a try

                      Axios Could you tell me how to remove Sane. In the software center there many paskage and I do not know the command for the terminal.

                        I remove sane and reboot and Solus find immediatly the printer and it's work. Thanks a lot.
                        Now I will re-intall sane because my mother use also the scanner.
                        But if I reinstall sane the printer does not work :-(
                        I will try to find another solution for my mother. thanks for your help and patience.

                          emmerich There suppose to be a workaround for that but I will
                          have to study that abit.
                          Sometimes sequence makes a difference but appears not in this case
                          Its doing what the article I read said..sheesh
                          I am glad we found the issue!!!

                          Oh you did it right removing it with software center

                            Question for the Mods
                            Why is sane taking control of his printer should it not be essential separate from printer
                            even tho its a combo printer.
                            when he installs sane back his printer stops working.

                            Thanks

                              Axios [not a mod but I believe from output above the OP has epsonscan2 installed for the scanner. If not, he should get it. it's flatpak and won't interfere with printer ever.]

                                  brent Since 2 people have fixed their printer issue by uninstalling sane I am
                                  not sure what approach is good.
                                  But that might be good idea in the meantime to try.
                                  I think TraceyC was asking about status in other thread awhile back so it will prob get looked at.
                                  Kinda in limbo swept enuf grey matter up off the floor..

                                      Axios Kinda in limbo swept enuf grey matter up off the floor..

                                      Nice job clearing out two today! fantastic.
                                      the sane issue very valid I hope they have a look

                                        After researching abit It appears sane issue maybe with udev Nix-os had more detailed about it
                                        arch just alittle.
                                        Seems to affect multi function printers the way they handle stuff different.
                                        I use seperate scanner printer never had any issues.
                                        I am getting a free working mutli color laser printer so all this will be in back my mind

                                        I am not an expert in informatics. But when I try live cd Linux mint the both, printer and scanner work properly. The graphics interface and software used seem the same between Solus and Mint. But maybe it is just for graphic interface. I hope it's can help.
                                        I will continue to use Solus for my personal computer :-)
                                        Thanks again for your patience.
                                        best regards