SC not installing correctly on 2012 R2 server

Hi,

We are using Sophos Central on our servers, most of which are 2012 R2. It's running fine on all but one server, which we noticed before Christmas that hadn't reported in to SC for several months. We reinstalled the endpoint client, and it briefly appeared to be working - registered itself in the SC console and updated. But after 5 minutes it stopped communicating.

We repeated this process last night, but exactly the same thing has happened again (see screenshot)

When I look in the endpoint client on the server, tamper protection isn't enabled, even though it shows as enabled in SC. And all of the settings are greyed out, even if I tick the 'Override' option. The client appears to be updating correctly, as per screenshot below, but not communicating with SC.

Any ideas how we can resolve this?

thanks

Dan