vmware datastore inaccessable

Our NAS tied to our VMWARE server does not now seem to be working.  If I run VSphere I get the yellow triangle warning me that the NAS is not working.  If I drill down into the datastore/NAS I get the second error.  I am a newbie to VMWARE, so I am not sure what the best next step is.  I have physically shutdown the NAS and then rebooted it.  All of the indicator lights come up and indicate the disks are all functional.  So I am not quite sure what to do next or even what is the best way to do it.  

How can I diagnose and fix this problem
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aovikingAuthor Commented:
Thanks,  I came across several of these.  I am looking at more direction, if possible.  This problem surfaced after a power failure and even though we have UPS' I suspect something happened with the NAS.
Can you access the NAS via other means?
Are you sure that you have connectivity?
If you lost power, (long shot) maybe the switch configuration was not saved and you lost the jumbo frames configuration.
Start with the basic, then move up.
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Can you ping the NAS from the ESXi server ?

What NAS are you using, and are you using NFS or iSCSI ?

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aovikingAuthor Commented:
We are using a Synology RS812+  I ran the console network troubleshooting and it came back and verified one address but then failed on resolution of the machine name.  It failed also on the machine ip which can be accessed by other machines on the network.  Is this a DNS issue?
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
NFS or iSCSI ?
aovikingAuthor Commented:
I believe it is iSCSI.   In any case, I think we solved it.  Somehow when the power rebooted the IP Configurations changed from Static to Dynamic, and the subsequent IP Address, Subnet Mask and default gateway values changed as well.  Once those were corrected, everything came up.
aovikingAuthor Commented:
Definitely this helped.
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