Do you experience problems during downloading?
Check your connection in Status and Interface settings window.
Use Test Server in Config > Servers.
We will probably ask you to do a test using only basic settings.
Do you experience problems during repair or unpacking?
Enable +Debug logging in the Status and Interface settings window and share the relevant parts of the log here using [ code ] sections.
[Wed Jun 20 18:45:31 2018] Out of memory: Kill process 20813 (sabnzbdplus) score 645 or sacrifice child
[Wed Jun 20 18:45:31 2018] Killed process 20813 (sabnzbdplus) total-vm:2415428kB, anon-rss:274120kB, file-rss:0kB, shmem-rss:0kB
[Wed Jun 20 18:45:31 2018] oom_reaper: reaped process 20813 (sabnzbdplus), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
So ... if SABnzbd gets Killed, check your dmesg for "Out of memory" ...