Looks like the WHMCS / Virtualmin integration has a weakness - a client cannot change their Virtualmin password from within WHMCS. This is bad because WHMCS provides a login to control panel link for users. If the user changes their password from Virtualmin, then, the link fails. So, would prefer to disable this in Virtualmin and use WHMCS for users to change their passwords. This functionality exists for other control panels.
So, my Virtualmin question is this - does Virtualmin have an interface that supports an external product like WHMCS to allow them to make a call and change a users Virtualmin password?
For me, the link is broken anyway, and if I click on "Login to Control Panel" as a client from WHMCS, it says "Your browser does not support cookies, which are required for this web server to work in session authentication mode"