In around modern time in the United States there was a super secret science project, unknown to the general public. They invented an experimental portal system, allowing to teleport people and goods between one super secret underground military base to another. First they tested the system with two portals, and it worked well. Then they added a third portal to the system, and then they were able to move people and goods between those three different locations, by selecting the destination portal from a computer. It all worked flawlessly, even teleporting between different states.
However when they tried to added a fourth portal, to extend their portal system, a certain accident happened. Apparently they were able to power on the fourth portal and connect it to their existing portal system successfully, or so they thought. An employee stepped onto one of their already existing portals, in order to be teleported to the newly installed portal. The technicians set the destination portal on the computer, and then pulled the level. The man disappeared, and did not appear on the other destination portal. Furthermore, ever since the fourth portal was activated, any people or goods that were sent from any already existing portal to any other portal were sent, but they never reappeared on the other side. Even if both the sending portal and the destination portal were among the former three portals which previously worked. At the same time strange vases and pots began getting received on their portals, which they clearly hadn't sent.
Little did they know, when they activated the fourth portal and connected it to their already existing portal system, their portal system got connected with an already existing portal system in a parallel universe. In that parallel universe, ancient East Asian civilizations had discovered magic/psychic powers, and after integrating such powers with technology they created many science fiction type inventions, one of which was a planet spanning portal system with thousands of gates on the alternate Earth.
Since the Area 52 portal system got connected with the parallel Earth's portal system, anything that they would send would be received in some portal on the parallel Earth, instead of going to the intended destination. Any people or cargo that they transported would eventually be arrested by the parallel Earth's authorities. Furthermore, occasionally something would come into one of the Area 52 portals.
In order for this plot to work, I have to explain why adding a fourth portal caused their already existing portal system (which worked fine with three portals) to connect with a portal system from that parallel universe. Why the number 4? What would be the quirks and features of that portal system for it to get connected like that?