In order to get rid of "Error 0×80092013: The revocation function was unable to check revocation because the revocation server was offline" you have to install base/delta CRLs on the client you want to connect to the VPN server...
However, it would seem that I have to frequently install the CRLs from my Certificate Authority server on my clients (every couple of days, not just once) - a task which is rather cumbersome. Is there a way to automate the CRL download/addstore or actually fix this issue (without disabling CRL check)?