problems accessing samba share through Xfce gui

[Paul Marwick via arch-general <arch-general@xxxxxxxxxxxxx>]

Arch Linux, fully updated,  running Xfce, installed on a Lenovo T420 
laptop. I’m having strange, intermittent problems accessing samba shares 
through the GUI.

The problem varies, no pattern that I can detect. Sometimes, clicking on 
the “Browse Network” icon in Thunar does nothing, eventually returning 
‘Failed to open “/” Timeout reached’ . Other times it will open the 
network view and allow me to double-click the Windows Network icon. 
Sometimes that is the last thing that happens (possibly followed by 
another timeout error, though that can take so long that I may have shut 
the machine down before it happens). If it gets past the main Windows 
network stage, it will show me any active workgroup. It may fail there, 
or it may give me a view of the machines in the workgroup. It may allow 
me to select a machine, and may show me the shares on the machine. If I 
double-click on a share, it will (sometimes) pop up the login dialog. If 
that fails, sometimes double-clicking a second time will show the login 
dialog.

If I am able to connect to a share, there is (sometimes) a further 
problem. Using the Thunar option to disconnect from the share works, but 
if I attempt to reconnect to the share, or connect to another share, 
instead of opening the share in Thunar, it opens VLC, which doesn’t 
understand what is going on and does nothing.

I have two other Arch installations on my laptop, plus two desktop 
machines which run Arch. None of the other installations have any 
similar problems. The Arch installs are all very similar in terms of how 
they were installed and the software they have on them. Also, the 
install which is giving me this problem developed it – originally it 
worked without any errors. I mad a mistake configuring the samba server 
on an Ubuntu 16.04 server and followed that up by attempting to access 
the share from my Arch install. This problem has been happening ever 
since then, but only on the one install.

I’ve checked the systemd journal and found absolutely nothing to help me 
diagnose the problem. This install does have on problem which shows 
consistently during boot - I get a core dump in the systemd journal from 
colord-sane (which is installed on the other installs as well). However, 
while the core dump happens on every boot, the samba problem only 
happens on some, so I don't think the problem comes from there.

I’m fairly sure that the problem is not Thunar itself (I’ve tried 
PcmanFM, which shows similar inconsistent behaviour – sometimes it will 
connect without problems, other times pcmanfm locks up and does nothing, 
has to be forced closed. I also installed gigolo, which also shows 
similar problems.

I think the problem is in one of the back-end programs which handles 
mounting the shares. I guess that includes gvfs, fuse and possibly 
d-bus. I’ve not managed to find an explanation of exactly what is used 
when mounting a share using the gui.

I should also mention that when this happens, I can mount the shares 
without problems from the command line, or using mount with suitable 
entries in /etc/fstab. Also, thinking that there might be something 
messed up in my user profile, I added another user and tested using that 
user. Problem is exactly the same  - sometimes the mount works without 
errors, others it fails in the same unpredictable manner.

While I could fix the problem by reinstalling, this is one of the few 
things I’ve ever hit in Arch that (so far), I’ve been unable to fix. I 
would really love to be able to fix it, but that means I need to have 
some way of diagnosing where the problem is. Any help would be very 
gratefully received.