I also have a Synology as one of 2 NAS boxes.
You need to turn Jumbo frame option off and that will give mtu 1500 (which is ok).
Setup of NFS is pretty easy.
Set NFS service on in Synology config.
Then select a share you want to make avail using NFS.
e.g. video
Then goto config panel, shared folder.
Select the folder you want to share over NFS.
Press on NFS priviliges on top.
Press create
Fill in your Mede8er ip number
Privilige read/write
Root squash no mapping
Enable asynchronous
You will see the file path on the bottom of this window. You need to use this name later on your mede8er.
On your mede8er:
Goto Network - NFS
Press Menu button, select Add
now fill in the ip number of your NAS
fill in the path (as mentioned above). e.g. /volume1/video
Thats it. You should now be able to enter on the saved NFS path.