Was that with a SMB mount, or dd also running on the Syno?
I’m gonna have to think about this. The only thing I can think of to try would be running iperf3 and dd at the same time. Maybe run the iperf from one of the other Veros while the dd from the one you’ve been testing from.
One other thought, have you rebooted your router/switch? Has the Syno had any updates lately?
Yes to all basically. Syno gets regular updates. Router has been rebooted recently. This is def a vero issue because things work from other devices. If I have to I will reinstall osmc. Been having issues for months and finally gave up trying to figure it out on my own
ok running iperf on vero4k+ and dd on vero 4k the iperf numbes went from 930mbits/sec to 120mbits/sec for a few seconds and then the vero4k basically froze and the vero4k+ went back to 930mbits/sec
also when the dd starts to copy again it coincides with a drop in iperf to about 130mbits/sec. then dd freezes and iperf goes back to 930mbits/sec
Wrote it and then went on for another hour 
Did you enable the samba share on the Synology?
Suggest to try checking with smbclient.
sudo apt install smbclient
smbclient -L 192.168.0.107
@gkron92 Before you go the path trying smb could check wehther NFSv4 is active on your Syno:
You can also check what NFS protocol will be used on a system mounted path, here an example from my system verifying that NFSv4.0 is the protocol both sides negotiated for ’ /mnt/tv_recordings’
root@osmc-vero4k:~# cat /etc/fstab
UUID=538214da-b9d1-4460-9e87-de3efcb5da0a /mnt/Intenso2766GB ext4 defaults 0 3
synologyds214se.fritz.box:/volume1/music /mnt/music nfs defaults,x-systemd.automount,noauto 0 0
synologyds214se.fritz.box:/volume1/photo /mnt/photo nfs defaults,x-systemd.automount,noauto 0 0
synologyds214se.fritz.box:/volume1/tv_recordings /mnt/tv_recordings nfs defaults,x-systemd.automount,noauto 0 0
root@osmc-vero4k:~# df
Filesystem 1K-blocks Used Available Use% Mounted on
devtmpfs 774712 0 774712 0% /dev
tmpfs 899232 41580 857652 5% /run
/dev/vero-nand/root 14499760 4081868 9658292 30% /
tmpfs 899232 0 899232 0% /dev/shm
tmpfs 5120 0 5120 0% /run/lock
tmpfs 899232 0 899232 0% /sys/fs/cgroup
/dev/sda1 2929761288 2624494668 275947584 91% /mnt/Intenso2766GB
/dev/sdb1 248864 6 248858 1% /media/F84A-4045
/dev/sdb2 15069064 3893220 10390644 28% /media/fcce3b5b-1f18-417e-ac9b-8ba9a7460e40
synologyds214se.fritz.box:/volume1/tv_recordings 2879613440 612361216 2267149824 22% /mnt/tv_recordings
synologyds214se.fritz.box:/volume1/music 2879613440 612361216 2267149824 22% /mnt/music
synologyds214se.fritz.box:/volume1/photo 2879613440 612361216 2267149824 22% /mnt/photo
tmpfs 179844 0 179844 0% /run/user/0
root@osmc-vero4k:~# mount -av
/mnt/Intenso2766GB : already mounted
/mnt/music : ignored
/mnt/photo : ignored
/mnt/tv_recordings : ignored
root@osmc-vero4k:~# umount /mnt/tv_recordings
root@osmc-vero4k:~# mount -v /mnt/tv_recordings
mount.nfs: timeout set for Thu Aug 27 13:40:03 2020
mount.nfs: trying text-based options 'vers=4.2,addr=10.10.10.25,clientaddr=10.10.10.21'
mount.nfs: mount(2): Protocol not supported
mount.nfs: trying text-based options 'vers=4.1,addr=10.10.10.25,clientaddr=10.10.10.21'
mount.nfs: mount(2): Protocol not supported
mount.nfs: trying text-based options 'vers=4.0,addr=10.10.10.25,clientaddr=10.10.10.21'
So, mount start swith highest NFS protocol version down to lowest and stops once the other side.confirms.
But I see that you’re on 4.9 test kernel … no idea whether this is really stable and might be the reason for such intermittent issues. From the log provided the stream is simply stalled
...
2020-08-26 23:22:13.274 T:3252675296 INFO: CVideoPlayerVideo - Stillframe detected, switching to forced 23.976024 fps
2020-08-26 23:22:13.275 T:3252675296 DEBUG: CPtsTracker: pattern lost on diff 208541.666667, number of losses 1
2020-08-26 23:22:13.425 T:3223278304 NOTICE: CVideoPlayerAudio::Process - stream stalled pts:2046.644 clock:2046.657
2020-08-26 23:22:16.887 T:3231671008 ERROR: ffmpeg[C09F62E0]: [matroska,webm] Read error
2020-08-26 23:22:26.921 T:3231671008 DEBUG: CDVDClock::SetSpeedAdjust - adjusted:0.000000
2020-08-26 23:22:26.921 T:3231671008 DEBUG: Previous line repeats 1 times.
2020-08-26 23:22:26.921 T:3231671008 INFO: Process - eof reading from demuxer
2020-08-26 23:22:26.921 T:3231671008 NOTICE: CVideoPlayer::OnExit()
...
well I was called a wimp… 
NFSv4.1 is enabled on my Synology but the domain field is blank. Does that matter?
The domain field is optional … but more interesting is what protocol version your Vero really uses with the Synology NAS, see the rest of my previous post.
On the Synology NAS I have set the packet size to 32KB at Files-Services->SMB/AFP/NFS->NFS->Advanced Settings.
If this is all set correct, I’m out of ideas … except the kernel 4.9. But to go back to OSMC release means you have to re-install the device. And if it would figure out afterwards, your bandwidth/network issue has an outer root cause, this re-installation would have been unnecessary.
packet size is set to 8kb for read/write. Change to 32?
in any case
when I do the mount -av command nothing happens…just goes back to the prompt…sorry not a linux guy at all just a regular user. do the rest of the commands anyway?
Ok. So I need to go back to fstab and then do these commands… 
I guess there are ways to figure it out with autofs but I am also not sure if that is your problem as you saw actually your whole network coming to a standstill when you did the test with the Vero 4k and the 4k+.
I still suggest to try samba mount as a first step