I'm in a similar position. I'm on my second NAS in the last 12 years. I've been very satisfied with their performance, but this kind of behavior is just completely unacceptable. I guess I'll need to look into QNAP or some other brand. Also, I think my four disc setup is in a RAID 5, but it might be Synology's proprietary version, so I'll need to figure out how to migrate off of that. I don't think I'll be able to just insert the drives in a different NAS and have it work.