Synchronisation is not working properly

Dear all
I’ve installed Nextcloud on a GNU/linux machine.
When I try to sync, it stops at one point.(I tried un-installing the client, re-installing, to no avail)
I’d like it to not stop and sync the entirety of the cloud…
And Nextcloud is telling me there is some errors (2x service unavailable, 8xoperation cancelled) , but the errors bear no resemblance with the problem I’m experiencing (it’s not as if it stops when it blocks on a file)…
Is it possible to send the log file/+print screen somewhere for you to see what I mean ?
Sorry to not be able to make myself clearer…
Please ask any question you need…
Thanking you in advance