The world is broken up into seven realms: Australia, North America, South America, Antartica, Asia, Europe, and Africa. Each realm is populated by large numbers of people, and travel between realms is commonplace. This form of travel occurs through a series of realm gates, one of which is located within each realm. This gates link to a massive, in-between realm that connects the smaller realms to each other. One must pass into this space in order to connect to a gate that will transport them to the realm of their destination.
Magitech has been developed by humanity, which has caused it to enter its industrial phase in history. Magitech is built by an individual or group of people infusing a particular item with their own mana, empowering it with certain properties it would not otherwise have been capable of. Society runs on this form of technology, such as computers, phones, cars, etc. It is available to all of the population and has become a center point of life. However, technology can only work within the realm that it was created. If taken to an alternate realm, it would not function. This prevents trade from occurring between realms, even though travel between them happens on a regular basis.
The reason it is set up in this way is because I wanted each realm to develop their technology independently from each other. Because of this, societies will sometimes develop their own form of similar products, while others would not be able to develop certain items at all. This would lead to differences in tech levels, with some realms being highly advanced and others being less modern and primitive. However, I can't justify why tech from one realm wouldn't work in another neighbor. Somehow linking the reason to mana made sense. However, humans also have mana and can pass through these realm gates just fine, as well as use magic with no issues.
How can mana prevent technology in one realm from working in another?