Two iPads and same network but not able to join same game

[familygamers]

Hi,

I have two iPads.

I have Dungeon Defenders installed on each iPad.

Each iPad has a separate account, either on GameSpy or on Game Center.

PROBLEM #1: I cannot use the LAN Game function.
Steps to reproduce:
On iPad #1 and iPad #2, force-close Dungeon Defenders (double-click hard button, find Dungeon Defenders, press the close icon). This ensures it is not running.
Load Dungeon Defenders on iPad #1.
iPad #1: Select "Online"
iPad #1: Select "Adventure" then "Next"
iPad #1: Select character and then "Start"
iPad #1: Select "LAN"
iPad #1: Select "Custom"
iPad #1: Shows "Searching". There aren't any games.
iPad #1: Select "Host game"
iPad #1: Go with default, "Player's game" and press "Okay"
iPad #2: Select "Online"
iPad #2: Select "Adventure" then "Next"
iPad #2: Select character then "Start"
iPad #2: Select "LAN"
iPad #2: Select "Quick"
iPad #2: Shows "Searching for games".
iPad #2: Shows "No games found, would you like to create one?"

Both iPads are connected to the same network in this scenario.
iPad #2: Press "No"
iPad #2: Select "Custom"
iPad #2: Shows "Searching for games"
iPad #2: Shows no games in list.
Remember, both iPads are on the same wireless network. There is also a laptop, a phone, and a desktop. All of these devices work normally.

PROBLEM #2: I cannot create an internet game on iPad #1 and join it from iPad #2. Or the opposite.
iPad #1: Select "Online"
iPad #1: Select "Adventure" then "Next"
iPad #1: Select character then "Start"
iPad #1: Press "Log In"
iPad #1: Select "Custom"
iPad #1: Select "Host Game"
iPad #1: Give it name of "Bellingham"
iPad #1: Shows "Creating game" then the tavern
iPad #2: Select "Online"
iPad #2: Select "Adventure", then "Next"
iPad #2: Select character then "Start"
iPad #2: Select "Log in"
iPad #2: Select "Custom"
iPad #2: Shows the game named "Bellingham"
iPad #2: Select the Bellingham game and press "Join Game"
iPad #2: Shows "Joining game"
iPad #2: Shows "Join Failed, Attempt to join game failed"

Remember, both iPads are on the same wireless network. This is absurd that two devices on the same network cannot join a game on the same network. Please advise on how to fix.

Network details: network is a MediaLink Wireless-N Router. uPnP is enabled. There's a firewall like you would expect, and connections are NAT to the internet. More details available if that's the problem.