If it occurs regularly enough, please look at web browser network activity. What browser is it?
Maybe you already use many browsers to access Duplicati, but not to retrieve to that device?
Basically, you retrieve data to the NAS?
As a side note, the web server inside Duplicati is being replaced (it’s old) but isn’t finished yet.
I’m not sure if there’s any way to tell if the current server is serving without looking at its traffic.
What else is or is not in the GUI? Usually when Duplicati is slow, About screen data is missing.
One clue from Home screen is in the top left corner, where “Beta” or whatever is slow to show:
That probably impedes the multiple-Duplicati problems where first gets 8200, second 8300, etc.
Still, you can probably view About → Show log to compare what’s there normally vs. when bad.
If it changes, then it switched server databases. File is Duplicati-server.sqlite if you want to look.
Although maybe app central did differently, databases are generally in ~/.config/Duplicati.
On some NAS, the potentially large job databases fill up root’s home directory, so go elsewhere.
--server-datafolder
Duplicati needs to store a small database with all settings. Use this option to choose where the settings are stored. This option can also be set with the environment variableDUPLICATI_HOME.
is one way to move Duplicati-server.sqlite, but a symbolic link can also get the database moved.
You should be able to use ps to find user it runs as, options provided, and even its environment.
Duplicati way to get some of this is the Database screen and UserName in About → System info.
Test screens that you can get to, as suggested, and especially see what Restore on the left has.
If its time is convenient, you could see if About → Show log → Live can see anything going on.