@Lucy_Hinnie glad you resolved it - and that seems to confirm it’s something about the local network setup 
The reason I asked about how you were starting OpenRefine is that you can add options to tell OpenRefine to use any proxy that is configured locally but the way this is done on Windows is different depending on how you start the system.
So just in case it is helpful you can see
Leaving some extra notes here in case anyone finds this issue in the future …
If you are starting via the icon on your desktop, that’s using “openrefine.exe” which means the options used on starting OpenRefine are the ones in the openrefine.l4j.ini file. The other option for starting OpenRefine on Windows is via refine.bat (Running OpenRefine | OpenRefine) and in that case the settings are taken from refine.ini instead.
For proxy use there are a few relevant settings:
-Djava.net.useSystemProxies=<true or false>
-Dhttp.proxyHost=<local proxy address>
-Dhttp.proxyPort=<local proxy port>
-Dhttp.nonProxyHosts=<any hosts to exclude from the proxy requests>
I can see that there have been various issues with the use of proxies with OpenRefine and a fix was contributed for using proxy servers with reconciliation which is included in the new (at time of writing) 3.7 beta release (see https://github.com/OpenRefine/OpenRefine/issues/3919 for the relevant issue description on GitHub)