delayed write failed vm->vm

I have a file server (win 2k12 r2) and a rds server (win2k8r2) and we've been having an issue with a dbase app when it tries to write to a specific database. In the event viewer it's throwing a 140 error: {Delayed Write Failed} unable to save the data on \\win2k12r2\path\to\db.dbf

I can't figure out where this is coming from other than possibly an issue with disk speed and proxmox.

My storage is a Synology NAS via NFS.

Anyone have any ideas?