(Having read the rules for the network forum this didn't seem to fit, hopefully this is the right place to post - sorry in advance if it's not.)

I am having intermittent problems in accessing my Brother_MFC-J5330DW multi-function inkjet. Often (especially if I'm in a hurry) a print job will just sit in the print queue and the message "In use -"Unable to locate printer."" appears under the name of the printer itself. I've had the same problem on the same computer in Mint Cinnamon 19.3, Ubuntu 20.04, and now in Kubuntu 20.04. Any time I think I've fixed it a day passes and the problem reappears. Sometimes reboots (printer and PC) fixes it, sometimes not.

In my current distro I've tried disabling the automatic printer detection of cups-browsed and assigning a static ip address to the printer in my router. I used that static ip when installing the printer and scanner manually. The printer configuration shows the connection as

dnssd://Brother%20MFC-J5330DW._ipp._tcp.local/?uuid=e3248000-80ce-11db-8000-3c2af4c206e4

I am now wondering if Network Manager isn't playing nicely with my hardware (details below), having come across posts saying that network manager can be "flaky" and suggesting replacing it with WICD.

So would a switch to WICD likely be worth trying?

Thanks

My PC is an Intel NUC8i5BEH Output of lspci:
NUC8i5BEH:~$ lspci
00:00.0 Host bridge: Intel Corporation 8th Gen Core Processor Host Bridge/DRAM Registers (rev 08)
00:02.0 VGA compatible controller: Intel Corporation Iris Plus Graphics 655 (rev 01)
00:08.0 System peripheral: Intel Corporation Xeon E3-1200 v5/v6 / E3-1500 v5 / 6th/7th/8th Gen Core Processor Gaussian Mixture Model
00:12.0 Signal processing controller: Intel Corporation Cannon Point-LP Thermal Controller (rev 30)
00:14.0 USB controller: Intel Corporation Cannon Point-LP USB 3.1 xHCI Controller (rev 30)
00:14.2 RAM memory: Intel Corporation Cannon Point-LP Shared SRAM (rev 30)
00:14.3 Network controller: Intel Corporation Cannon Point-LP CNVi [Wireless-AC] (rev 30)
00:16.0 Communication controller: Intel Corporation Cannon Point-LP MEI Controller #1 (rev 30)
00:17.0 SATA controller: Intel Corporation Cannon Point-LP SATA Controller [AHCI Mode] (rev 30)
00:1c.0 PCI bridge: Intel Corporation Cannon Point-LP PCI Express Root Port #1 (rev f0)
00:1c.4 PCI bridge: Intel Corporation Cannon Point-LP PCI Express Root Port #5 (rev f0)
00:1d.0 PCI bridge: Intel Corporation Cannon Point-LP PCI Express Root Port #9 (rev f0)
00:1d.6 PCI bridge: Intel Corporation Cannon Point-LP PCI Express Root Port #15 (rev f0)
00:1f.0 ISA bridge: Intel Corporation Cannon Point-LP LPC Controller (rev 30)
00:1f.3 Audio device: Intel Corporation Cannon Point-LP High Definition Audio Controller (rev 30)
00:1f.4 SMBus: Intel Corporation Cannon Point-LP SMBus Controller (rev 30)
00:1f.5 Serial bus controller [0c80]: Intel Corporation Cannon Point-LP SPI Controller (rev 30)
00:1f.6 Ethernet controller: Intel Corporation Ethernet Connection (6) I219-V (rev 30)
6d:00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd NVMe SSD Controller SM981/PM981/PM983
6e:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS522A PCI Express Card Reader (rev 01)

The choice of network management framework is unlikely to make a difference here. Assuming that you have a stable wireless network environment, I would concentrate your efforts on the printer configuration instead. Usually, I would not expect a problem with using the CUPS dnssd backend, but it does rely on Avahi working properly, and in a busy network that might cause some issues with reliable discovery perhaps. Also, I've seen similar behaviour when hosts (such as printers) are left inactive for some time as you describe.

You could reconfigure CUPS to reach the printer by IP address instead. The ipp backend should be ok to use. For example, assuming the printer is assigned with 192.168.0.100 then the URI would look like
FWIW, a similar thread...
https://forums.linuxmint.com/viewtopic.php?t=314881

Thanks ferrari. (BTW, as an aussie, maxima congrats on the recent T20 comp).

How exactly do I best reconfigure CUPS? (I'm surprised it doesn't already use the IP address 'cos that's how I tried to set it up.)

PS, the similar thread -that was me. But it seemed more of a work-around than a fix. I do a LOT of searching before posting a query but couldn't find this or I'd have tried to follow it again. But only one similar thread? Why this only happening to me? I've been using Linux for 20+ years and have rarely had problems with printing.

Cheers. Use the CUPS web interface to edit the configuration as required.

Well it was just the result of a quick online search. Doesn’t mean there aren’t others of course.

Not sure why Avahi isn’t working consistently in your network environment. I use it in my home and work networks without issue. However, sometimes simply restarting the hosts does the trick.

This works for me on both desktop and laptop:

Brother MFC-J4510DW CUPS (color)
lpd://192.168.1.113/BINARY_P1

Season to taste.

After 15 months of battling with this I'd thought I was getting closer but - sigh - it's still not working.
The CUPS web interface shows:

Current Connection: ipp://192.168.0.14:631/ipp/print

This, as far as I can know, includes the appropriate ip address.

Windows laptops print over wifi to this printer fine, and my linux machine does too, occasionally. Being an intermittent problem definitely makes it harder to fix.

Thanks, but I'm not sure how to proceed with this. Which bits go where?

Also, the work-around in https://forums.linuxmint.com/viewtopic.php?t=314881 seems not to be working this time.

The same way you did with reconfiguring for ipp. Use the CUPS web interface.

Please report back with output from
Let's check the printer status.

Also, demonstrate that you can reach the printer with a ping.

NUC8i5BEH:~$ lpstat -t
scheduler is running
system default destination: Brother_MFC-J5330DW
device for Brother_MFC-J5330DW: lpd://192.168.0.14/binary_p1
Brother_MFC-J5330DW accepting requests since Thu 11 Mar 2021 03:38:53
printer Brother_MFC-J5330DW is idle. enabled since Thu 11 Mar 2021 03:38:53
The printer is not responding.

Note that I changed the connection to lpd://192.168.0.14/binary_p1 as per rinaldij's post.(didn't work)

Just googling to find out how to ping a printer . . .

NUC8i5BEH:~$ ping 192.168.0.14
PING 192.168.0.14 (192.168.0.14) 56(84) bytes of data.
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
ping: sendmsg: Operation not permitted
^C
--- 192.168.0.14 ping statistics ---
27 packets transmitted, 0 received, 100% packet loss, time 26612ms

This indicates that you have a firewall blocking outbound ICMP packets.

lpd uses port 515. If your firewall is also blocking outgoing traffic on that port printing will not work.

As a frame of reference my Brother printer is configured exactly as per rinaldij's post and it works fine assuming you installed the driver correctly.

I thought as much, and have been furiously researching this. As far as I can tell the firewall is off:

NUC8i5BEH:~$ sudo ufw status
Status: inactive

But maybe not . .

NUC8i5BEH:~$ sudo iptables -S
[sudo] password for rjh:
-P INPUT ACCEPT
-P FORWARD ACCEPT
-P OUTPUT ACCEPT
-A INPUT -s 103.137.12.219/32 -i wlp0s20f3 -j ACCEPT
-A INPUT -s 103.137.12.219/32 -i eno1 -j ACCEPT
-A INPUT -i wlp0s20f3 -j DROP
-A INPUT -i eno1 -j DROP
-A OUTPUT -d 103.137.12.219/32 -o wlp0s20f3 -j ACCEPT
-A OUTPUT -d 103.137.12.219/32 -o eno1 -j ACCEPT
-A OUTPUT -o wlp0s20f3 -j DROP
-A OUTPUT -o eno1 -j DROP

Trying to read through iptables basics but am feeling incredibly dumb at the moment. I've installed Gufw Firewall, a GUI firewall controller. It also says the firewall is inactive. Am thinking about activating it with default rules to see what happens. Is this a good idea?