I sometimes get into a situation where Software Update simply displays a message where it says it could not connect to any Apple servers. How can I force it to check again after I solve the connectivity issue?
Sometimes selecting another item in the System Preferences and then switching back to Software Update helps, but today it didn't.
In some more detail, my work Mac is on a VPN which blocks connections until I supply my VPN password. This seems to wedge Software Update into a situation where so far my only remedy seems to have been to close it and wait for an unspecified period of time and then try again; however, when there is an important security update, this is clearly unattractive or even a violation of company policy.
I am currently on MacOS Mojave but this has been a problem for me for several years already.