I have rather unusual problem in that no one else has ever heard of it. I have software based RAID-5 array on a old AMD-8350 with a GA-990FXA-UD5 motherboard. When ever I write to the array from over the network, samba or sftp/scp, the network dies after about 5 minutes, give or take. It only does then when I'm writing to the array over the network. Copying files to the array internally, everything works fine. I can read from the array over the network just fine. This seems to be the only log error.
Jun 24 15:49:12 jackass NetworkManager[5480]: <info> [1561409351.9994] device (enp8s0): statechange: unavailable -> disconnected (reason 'carrier-changed', sys-iface-state: 'managed')
Writing to RAID over network, kills network
Re: Writing to RAID over network, kills network
Congratulations and it sucks to be youI have rather unusual problem in that no one else has ever heard of it.
It;'s fairly unlikely that the correlation between the write happening and the network death is accurate - unless there is a bucket load of buffering going on (in which case you have to much hardware!)the network dies after about 5 minutes
The log message suggests the carrier has dropped on the connection (well it's changed and either the carrier is there or not). Replace labels and try a different port on the switch (or even better use something that is known to be working well).
More info may be gleamed from:
journalctl -u NetworkManager
and (possibly):
dmesg