There could be many reasons. The first to check is of course the network connection and many other common causes.

The possible reason that is not quite obvious is the fact that your are visiting V-NET using Safari that is in the private browsing mode. If this is the case, which is likely to be if your system defaults to such a mode (like it can be done in IPad mini, etc.), then visit V-NET in a new window or tab of Safari in non-private browsing mode can solve the problem.