Have had this a few times on different servers and I keep forgetting the specifics of the (very quick and easy) solution.
Symptoms are that the server won’t talk to anything over the network, nor can you talk to the server from anywhere on the network. IPConfig output looks fine, network link is up, network switches all look fine. You try other NICs on the server but none work.
Then you notice the IPSec service is stopped despite being set to automatic start.
Check to see if:
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\IPSec
is missing. If it’s not present, there’s your problem. Run the following command to re-populate the registry:
regsvr32 polstore.dll
Then you can start the IPSec service and you’re back in business. Usually a reboot is a good idea if you’re joined to a domain so that the computer can log on and apply any group policies.
Robin CM's IT Blog 