NAS Disconnecting video editing

We use a Synology NAS to edit footage from. Its been fine for near on 2 years. I updated (mistake) 2 weeks ago and then all of a sudden monday monring the server is disconnecting whenever it needs to do something ie: Exporting a video, reading the timeline, importing photos. It doesnt seem to matter about the file size. It just disconnects. Any ideas here? its only an issue with the NAS. Other drives like the Black Magic Cloud unit is fine. Also transfer speeds have slow right down