Can't Map Network Drive

[kernkeller]

I plugged my DS211J into my router using ethernet cable. Configured it for raid 0 and loaded with my data. For about a month I was able to map a drive but no longer can see it on my network. I can't even ping it. When I use synology assistant it finds it and I am able to get in but I still can't find it on my network. I can see it assigned an ip address and attached to my router. Any ideas why I can't see it on the network?