Media disconnected when opening premiere - connected to NAS

Hello community, 

We have three edit workstations, two running Mojave and one on high sierra. They are all connected to Synology NAS on 10Gbe Network (being supplied to the computer by an Akitio Thunderbolt 2 - 10Gbe Adapter) which has been working great since the beginning of the year. All systems are running Premiere 13.1.4.

For the past week we have been experiencing a problem where the graphic media (psd's, jpegs, pngs) are disconnected when we open up premiere. The files have not been moved and the names have not been changed. When you browse with media browser the last known path is the actual path for the files but for some reason it does not connect. Our NAS is less than a year old and like I said has been working like a charm until about a week ago. I can't recall when we updated to 13.1.4 but it happened way after that. 

Is anyone else experiencing this issue and has anyone found a workaround for this. I would really appreciate any help as we are in the busiest season and there are so many projects currently on the line. If you need any other information please let me know. 

Thanks,

wilhelm