So we had a power failure, this one so long it sucked the UPS:es dry and I had a machine (Server 2008, non R2 even) that didn't shut down in time and it went down in an uncontrolled fashion. Ever since that happened, I'm unable to RDP into the machine, and remote backups over the network fails also (the software has marked the server offline). However, it is still serving up shared files and folders, doing DNS and DHCP duties and so forth. It's apparently only (some?) incoming connections that fail.

Looking at the network connections, it has the usual static IP set, it has a gateway set, I deleted arp entries as well just in case that had something to do with it. I can ping the machine just fine, but can't connect with RDP and so on.

I fired up the diagnostics function on the network just to see what it says, and get a "network connection doesn't have a valid IP configuration"; I didn't want to take the network offline at the time so I canceled for now - but the network is clearly working and moving data all the time and answers pings. So now I'm confused. The machine has been rebooted since but still behaves in this fashion. Any ideas what to look at from here?

Hi,

According to your description, my understanding is that it failed to remote connect to/remote backup the server(WS 2008) after an abnormal shutdown.

You may reference link below for possible causes and corresponding troubleshooting steps:
https://support.microsoft.com/en-us/kb/2477133

If the problem persists, is there any error message prompted when remote connection failed? You may open Event Viewer and confirm that if any related event has been logged. 

>the software has marked the server offline.
What the software do you mean?

Best Regards,
Eve Wang