So where does the problem manifest? This seems correct.
I have four Jami devices on my LAN, plus the Jami server (so five in total). The four were created and linked in the standard way, whilst the Jami server was created and linked as described above. Only the Jami server is on all the time; often it is the only device that is on. Of the other four, one is running Win10, two are running Ubuntu, and one is running Debian. The Linux devices list all of the other devices except the server. Only the Win10 machine shows all of the other devices including the server. In addition to being the only Windows machine, it also happens to be the first Jami device I created, so all of the others are linked from it, either directly or indirectly. It is also the case that the Virtual Box machine I created as a stepping stone to creating the server ran on the Windows machine. However, it is not just remembering the shut down Virtual Box machine, because if the server is not running, it’s not listed in the linked devices. So there may be some useful clues there, but they may be false leads.
Update 1: After a very long time, the server has now appeared on the lists of two of the Linux machines (one Ubuntu, one Debian); one still does not list it.
Update 2: Now it’s disappeared from the Debian machine. Given that Raspberry Pies are not exactly speedy, is the problem caused by a timeout that is set too short?
OK, I’ve figured it out. It’s a flaw in the UI design. The list of linked devices is scrollable within the main window, which is also scrollable. However, whilst the main window has a scroll bar, the list does not. Not only does this mean that you cannot see if there are extra items in the list that must be scrolled to, it also means you can only scroll to them using a scroll wheel. And even if a scroll wheel is available, it will be the main window that gets scrolled if the mouse pointer is in the wrong place. In my specific case, the server was always at the bottom of the list and therefore not visible if there was a sufficient number of devices switched on, whilst all the other devices were always visible (the list is not in alphabetical order). The only way I got to see the server at the bottom of the list was if there were not too many devices in the list or the device had a mouse with a scroll wheel or a touch-pad with a scroll wheel substitute and the mouse pointer was in the right place. Should be easy enough to fix, but what’s the best way to report it?
Another way to see the bottom of the list is to use the tab and the up and down arrow keys. The Qt used by Jami has a lot of bugs in terms of interactive logic.