can't access network printer since 20.04

[xzu]

I can access my network printer with all previous LTS-ubuntu version, but not since 20.04.

Normally, system-config-printer can found it with search functionality.
The expected result is:
smb://freebox/Brother%20DCP-J752DW

But in 20.04 I can't because System-config-printer ask for a password to access workgroup.
But there is NO password!
The printer is shared without identification needed.

I still have ubuntu16.04 on same machine and I am forced to print with it.
I give the output of system-config-printer --debug file with 16.04 if you want to compare with 20.04.

I have installed python3-smbc (1.0.15.6-2build2) to have the search functionality (software-center proposed to install it but can't!).
Then I have allowed samba with sudo ufw allow samba because system-config-printer ask it to try to access printer.

:~$ lsb_release -rd
Description: Ubuntu 20.04.1 LTS
Release: 20.04

:~$ apt-cache policy system-config-printer
system-config-printer:
  Installé : 1.5.12-0ubuntu1
  Candidat : 1.5.12-0ubuntu1
 Table de version :
 *** 1.5.12-0ubuntu1 500
        500 http://fr.archive.ubuntu.com/ubuntu focal/main amd64 Packages
        500 http://fr.archive.ubuntu.com/ubuntu focal/main i386 Packages
        100 /var/lib/dpkg/status

Printer: brother DCP-j752DW, cups drivers from brother site.
Server: a box, freebox4k-mini (from "free" french ISP) connected via USB to the printer.
I found other people having same problem with other hardware (server and/or printer).
I can't use ubuntu20.04 with this issue.

Thanks.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: system-config-printer 1.5.12-0ubuntu1
ProcVersionSignature: Ubuntu 5.4.0-47.51-lowlatency 5.4.55
Uname: Linux 5.4.0-47-lowlatency x86_64
ApportVersion: 2.20.11-0ubuntu27.8
Architecture: amd64
CasperMD5CheckResult: skip
CupsErrorLog:
 E [16/Sep/2020:15:25:11 +0200] Unknown directive JobPrivateAccess on line 125 of /etc/cups/cupsd.conf.
 E [16/Sep/2020:15:25:11 +0200] Unknown directive JobPrivateValues on line 126 of /etc/cups/cupsd.conf.
 E [16/Sep/2020:15:25:11 +0200] Unknown directive SubscriptionPrivateAccess on line 127 of /etc/cups/cupsd.conf.
 E [16/Sep/2020:15:25:11 +0200] Unknown directive SubscriptionPrivateValues on line 128 of /etc/cups/cupsd.conf.
CurrentDesktop: XFCE
Date: Wed Sep 16 15:34:36 2020
Lpstat:
 device for CUps-USB: cups-brf:/
 device for CUPSReseau: lpd://mafreebox.freebox.fr
 device for DCP-J752DW: lpd://0.0.0.0/binary_p1
 device for test: socket://mafreebox.freebox.fr:9100
Lsusb:
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 002 Device 003: ID 058f:9360 Alcor Micro Corp. 8-in-1 Media Card Reader
 Bus 002 Device 002: ID 046d:c03d Logitech, Inc. M-BT96a Pilot Optical Mouse
 Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Lsusb-t:
 /: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ohci-pci/10p, 12M
     |__ Port 1: Dev 2, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
     |__ Port 8: Dev 3, If 0, Class=Mass Storage, Driver=usb-storage, 12M
 /: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/10p, 480M
MachineType: To Be Filled By O.E.M. To Be Filled By O.E.M.
PackageArchitecture: all
Papersize: a4
PpdFiles:
 test: Brother DCP-J752DW CUPS
 CUPSReseau: Brother DCP-J752DW CUPS
 CUps-USB: Brother DCP-J752DW CUPS
 DCPJ752DW: Brother DCP-J752DW CUPS
 DCP-J752DW: Brother DCP-J752DW CUPS
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-47-lowlatency root=UUID=0a780a26-4ab8-45b9-80b7-41f505936637 ro splash quiet
SourcePackage: system-config-printer
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 09/19/2011
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: P1.60
dmi.board.name: N68C-S UCC
dmi.board.vendor: ASRock
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: To Be Filled By O.E.M.
dmi.chassis.version: To Be Filled By O.E.M.
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrP1.60:bd09/19/2011:svnToBeFilledByO.E.M.:pnToBeFilledByO.E.M.:pvrToBeFilledByO.E.M.:rvnASRock:rnN68C-SUCC:rvr:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.:
dmi.product.family: To Be Filled By O.E.M.
dmi.product.name: To Be Filled By O.E.M.
dmi.product.sku: To Be Filled By O.E.M.
dmi.product.version: To Be Filled By O.E.M.
dmi.sys.vendor: To Be Filled By O.E.M.

[xzu (xzurukneg)]

Here the output of system-config-printer --debug with 16.04 (working version).
It can found the printer without problem or asking password.
So I think this problem is a regression.

[cappa72 (cappa72)]

Same issue on my computes + NAS, with Ubuntu 20.04.
I applied the same settings that in the case of 16.04.
Result: 20.04 - nothing is printed. 16.04 - print without any question or issue.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[fir (sylvain-iob-8)]

Exactly same problem with epson sx400 on freebox server

[xzu (xzurukneg)]

In fact the problem seem to be here since ubuntu 18.04. (my mistake in 1st post)
But everybody don't care because of WIFI.
But if you don't want wifi, it's a very bad news.
Thanks anyway.