What is the server address? It's possible you are connecting to a "round robin" network where 1 of several is not accepted. Or, it could be that the server's certificate is now expired. In options/connect/options/ssl see if it helps to change from "skip" to "display invalid for approval". Unfortunately there's not a way to have the auto-accept be on a per-network basis. If you do make it "auto-accept" in order to connect, you can click on the "certificate" choice in status window to show what it looks like, to see what's going on. Note that it doesn't tell what type of underlying cipher is being used in the connect with the server.