Unable to edit files on Synology NAS after time

Hi I have a DS920+ on DSM 7.0

When i mount my share in finder either using AFP or SMB i can save new files and i can edit existing files no problem. A few hours later i will open a file on the share and make changes to it and click save and my mac will say "Unable to save" there is no way to fix this. I can still save new files, so i end up having to duplicate my file and save my changes that way. or i can save it to my Mac and then copy to the NAS and overwrite the original. The only way to fix it is to unmount the share and re-mount it.

This is a pain the butt as i have shortcuts on my finder left side that disappear when i unmount the share, and then i have to redo the shortcuts for my most used folders.

Has anyone experienced this?