For example on my home instance i visit never before visited URL: https://lemmings.world/c/qbittorrent@lemmy.ml
(I suspect that the home instance server were not aware about this external community at the time i have tried)
and it says "There was an error on the server. Try refreshing your browser." ... "The server returned this error: unknown."
Yet when i refresh/reload the page using F5 key like 1-2 seconds later, it loads the external community.
Can this be fixed so it reloads the page automatically or does not show this "unknown" error page and loads the external community directly even with some delay, so it does not confuse user and save the time?
You're right about the cause: Lemmy's front-end isn't giving its backend enough time to do everything it needs to do for an unfamiliar commentary.
It works better if you copy / paste the link into Search. MBin effectively redirects all these links to its Search anyway, so maybe that's an option.