When a fixed gate points to an invalid destination, it will "successfully" create the portal.
This portal will not function; if a player enters, the gate will destroy its iris yet not teleport the player.
If the gate was an A gate, the iris will remain active, and the player will be sent to the iris' associated dimension.

If the destination portal is created, that newly-created portal will function as expected.
However, the original portal, despite now having a valid destination, will still be broken.
(with a gates still sending players to their associated dimensions).

Repro Steps (Scenario One):

1. On an EMPTY NETWORK, create the following portal:

Example1
Example2
NetName
A

Try to enter this portal (you will end up in the nether if you used a nether gate).

2. Try sending a minecart through that portal.
   (it will get stuck in an infinite TP loop for some reason).

3. On a different axis, create the following portal:

Example2
Example1
NetName
A

Try to enter Example2 (this new portal); (you will exit from Example1 -- i.e. it will work normally).
Try to send a minecart through Example2 (this new portal); (it will bounce out the opposite direction -- i.e. get rejected).

4. Try to enter Example1 again.
   You will end up in the nether again.

Repro Steps (Scenario Two)

1. On an EMPTY NETWORK, create the following portal:

Example1
Example2
OtherNet

Activate the portal and try to enter it
(The iris mat will be destroyed and you will still be in the same place).

2. On a different axis, create the following portal:

Example2
Example1
NetName

3. Activate Example2 (this new portal) and enter it; (you will exit from Example1 -- i.e. it will work normally).

4. Try to activate Example1 and enter it again.
   It will fail in the exact same way as before.

This is now known to be a duplicate of #111