Cannot get full read-write speed to share mounted in NFS in VM

So here is my setup:

• Unraid 6.8.2, connected directly in my router at 1Gbps with a static IP
• User share name 'ZZZ' created in Unraid with Cache set to Yes
• VM running Lubuntu 18.04
  • vdisk is in /mnt/user/domains/MyVM/vdisk1.img and currently resides on cache drive
  • uses Network Bridge br0
  • network connection inside the VM is set with a static IP in the same subnet as my Unraid and other machines on my network (192.168.1.0/24)
  • mounted share 'ZZZ' inside my VM with NFS like this in fstab: 192.168.1.94:/mnt/user/ZZZ   /home/myname/ZZZ   nfs  rw,hard,intr,rsize=8192,wsize=8192,timeo=14 0 0

When I run a speed test from inside the VM at the root mount point (which in on the vdisk in my cache drive) I get very good results:

myname@MyVM:/$  sudo dd if=/dev/zero of=./speedtest bs=8k count=100k; sudo rm -f ./speedtest
[sudo] password for myname: 
102400+0 records in
102400+0 records out
838860800 bytes (839 MB, 800 MiB) copied, 1.18783 s, 706 MB/s

However, when I go into my mounted share, I get pretty poor results compared to what I expected, it looks like to have a bottleneck somewhere:

myname@MyVM:~/ZZZ$ sudo dd if=/dev/zero of=./speedtest bs=8k count=100k; sudo rm -f ./speedtest
102400+0 records in
102400+0 records out
838860800 bytes (839 MB, 800 MiB) copied, 8.1232 s, 103 MB/s

I already checked that when I run this test it writes to the cache drive, so that is not a "writing to the array" issue. I think it is a network issue since the speed I get is near the limit of a 1Gbps link, but I can't find how to resolve it.

Any idea ?