Like already mentioned, you will have to contact your network team. Just for reference, my iPad connects to my office network through VPN when I'm out and about.
Our network is shielded from the outside save only a couple of us that have VPN access. That access is physically monitored by some really bored guy watching a connection monitor listing: kinda looks like an automated Tetris in reverse, with extra pretty colors.
iPads can and do connect through VPN, again we have several. We really cannot help without knowing specific information about your network.